diff --git a/src/Controls/SETextBox.cs b/src/Controls/SETextBox.cs
index 0d0a3f8d5..3b52cadd5 100644
--- a/src/Controls/SETextBox.cs
+++ b/src/Controls/SETextBox.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Drawing;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 
 namespace Nikse.SubtitleEdit.Controls
diff --git a/src/Controls/TimeUpDown.cs b/src/Controls/TimeUpDown.cs
index acdea489a..61cbec38a 100644
--- a/src/Controls/TimeUpDown.cs
+++ b/src/Controls/TimeUpDown.cs
@@ -1,4 +1,5 @@
-using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Core;
+using Nikse.SubtitleEdit.Logic;
 using System;
 using System.Globalization;
 using System.Windows.Forms;
diff --git a/src/Logic/Extensions.cs b/src/Core/StringExtensions.cs
similarity index 78%
rename from src/Logic/Extensions.cs
rename to src/Core/StringExtensions.cs
index 4be15fb2c..1732981f7 100644
--- a/src/Logic/Extensions.cs
+++ b/src/Core/StringExtensions.cs
@@ -1,12 +1,11 @@
-using System;
+using System;
 using System.Text;
 
-namespace Nikse.SubtitleEdit.Logic
+namespace Nikse.SubtitleEdit.Core
 {
-    public static class Extensions
+    internal static class StringExtensions
     {
-
-        public static bool StartsWith(this String s, char c)
+        public static bool StartsWith(this string s, char c)
         {
             return s.Length > 0 && s[0] == c;
         }
@@ -16,7 +15,7 @@ namespace Nikse.SubtitleEdit.Logic
             return sb.Length > 0 && sb[0] == c;
         }
 
-        public static bool EndsWith(this String s, char c)
+        public static bool EndsWith(this string s, char c)
         {
             return s.Length > 0 && s[s.Length - 1] == c;
         }
@@ -35,6 +34,5 @@ namespace Nikse.SubtitleEdit.Logic
         {
             return source.IndexOf(value, comparisonType) >= 0;
         }
-
     }
 }
diff --git a/src/Forms/ChangeCasing.cs b/src/Forms/ChangeCasing.cs
index ed57a8029..80b02146e 100644
--- a/src/Forms/ChangeCasing.cs
+++ b/src/Forms/ChangeCasing.cs
@@ -1,4 +1,5 @@
-using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Core;
+using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Dictionaries;
 using System;
 using System.Collections.Generic;
diff --git a/src/Forms/ChangeCasingNames.cs b/src/Forms/ChangeCasingNames.cs
index 3d2f19c7e..57a06c941 100644
--- a/src/Forms/ChangeCasingNames.cs
+++ b/src/Forms/ChangeCasingNames.cs
@@ -1,4 +1,5 @@
-using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Core;
+using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Dictionaries;
 using System;
 using System.Collections.Generic;
diff --git a/src/Forms/EffectKaraoke.cs b/src/Forms/EffectKaraoke.cs
index 746ee6a4e..cbfe51f23 100644
--- a/src/Forms/EffectKaraoke.cs
+++ b/src/Forms/EffectKaraoke.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Drawing;
 using System.Text;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 
 namespace Nikse.SubtitleEdit.Forms
diff --git a/src/Forms/FindSubtitleLine.cs b/src/Forms/FindSubtitleLine.cs
index 9724fb63c..acbd134a2 100644
--- a/src/Forms/FindSubtitleLine.cs
+++ b/src/Forms/FindSubtitleLine.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using System.Collections.Generic;
 using System.Drawing;
diff --git a/src/Forms/FixCommonErrors.cs b/src/Forms/FixCommonErrors.cs
index 14637a935..3ec1e0c5c 100644
--- a/src/Forms/FixCommonErrors.cs
+++ b/src/Forms/FixCommonErrors.cs
@@ -1,4 +1,5 @@
-using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Core;
+using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Dictionaries;
 using Nikse.SubtitleEdit.Logic.Forms;
 using Nikse.SubtitleEdit.Logic.Ocr;
diff --git a/src/Forms/GoogleTranslate.cs b/src/Forms/GoogleTranslate.cs
index 0bc2ce4a9..15eb4ebf2 100644
--- a/src/Forms/GoogleTranslate.cs
+++ b/src/Forms/GoogleTranslate.cs
@@ -6,6 +6,7 @@ using System.Net;
 using System.Text;
 using System.Text.RegularExpressions;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using System.Xml;
 
diff --git a/src/Forms/ImportSceneChanges.cs b/src/Forms/ImportSceneChanges.cs
index 67d0e2a71..2645686ec 100644
--- a/src/Forms/ImportSceneChanges.cs
+++ b/src/Forms/ImportSceneChanges.cs
@@ -4,6 +4,7 @@ using System.Drawing;
 using System.IO;
 using System.Text;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 
 namespace Nikse.SubtitleEdit.Forms
diff --git a/src/Forms/ImportText.cs b/src/Forms/ImportText.cs
index 91d3e66b3..d601a6a32 100644
--- a/src/Forms/ImportText.cs
+++ b/src/Forms/ImportText.cs
@@ -6,6 +6,7 @@ using System.IO;
 using System.Text;
 using System.Windows.Forms;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 
 namespace Nikse.SubtitleEdit.Forms
diff --git a/src/Forms/MergeShortLines.cs b/src/Forms/MergeShortLines.cs
index cea7f77f5..97ae01a1d 100644
--- a/src/Forms/MergeShortLines.cs
+++ b/src/Forms/MergeShortLines.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Drawing;
 using System.Text;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 
 namespace Nikse.SubtitleEdit.Forms
diff --git a/src/Forms/ModifySelection.cs b/src/Forms/ModifySelection.cs
index 3af1477ad..d9710f8b6 100644
--- a/src/Forms/ModifySelection.cs
+++ b/src/Forms/ModifySelection.cs
@@ -1,4 +1,5 @@
 using Nikse.SubtitleEdit.Controls;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using System;
 using System.Drawing;
diff --git a/src/Forms/NetworkChat.cs b/src/Forms/NetworkChat.cs
index 3dec6a867..7ec6741cc 100644
--- a/src/Forms/NetworkChat.cs
+++ b/src/Forms/NetworkChat.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Networking;
 
diff --git a/src/Forms/OCRSpellCheck.cs b/src/Forms/OCRSpellCheck.cs
index 65d889ce6..5beee8e95 100644
--- a/src/Forms/OCRSpellCheck.cs
+++ b/src/Forms/OCRSpellCheck.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Drawing;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 
 namespace Nikse.SubtitleEdit.Forms
diff --git a/src/Forms/OpenVideoDvd.cs b/src/Forms/OpenVideoDvd.cs
index c586157b6..5f229bb9d 100644
--- a/src/Forms/OpenVideoDvd.cs
+++ b/src/Forms/OpenVideoDvd.cs
@@ -1,4 +1,5 @@
-using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Core;
+using Nikse.SubtitleEdit.Logic;
 using System;
 using System.Drawing;
 using System.IO;
diff --git a/src/Forms/RemoveTextFromHearImpaired.cs b/src/Forms/RemoveTextFromHearImpaired.cs
index 681eca32e..3999d21d9 100644
--- a/src/Forms/RemoveTextFromHearImpaired.cs
+++ b/src/Forms/RemoveTextFromHearImpaired.cs
@@ -1,4 +1,5 @@
-using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Core;
+using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Forms;
 using System;
 using System.Collections.Generic;
diff --git a/src/Forms/SetSyncPoint.cs b/src/Forms/SetSyncPoint.cs
index faab96e14..3ca3a1732 100644
--- a/src/Forms/SetSyncPoint.cs
+++ b/src/Forms/SetSyncPoint.cs
@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.VideoPlayers;
 using System.Drawing;
diff --git a/src/Forms/Settings.cs b/src/Forms/Settings.cs
index 5b521096c..361ca004b 100644
--- a/src/Forms/Settings.cs
+++ b/src/Forms/Settings.cs
@@ -1,4 +1,5 @@
-using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Core;
+using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Dictionaries;
 using Nikse.SubtitleEdit.Logic.VideoPlayers;
 using System;
diff --git a/src/Forms/SpellCheck.cs b/src/Forms/SpellCheck.cs
index 94ce491b5..268620aa0 100644
--- a/src/Forms/SpellCheck.cs
+++ b/src/Forms/SpellCheck.cs
@@ -1,4 +1,5 @@
-using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Core;
+using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Dictionaries;
 using Nikse.SubtitleEdit.Logic.Enums;
 using Nikse.SubtitleEdit.Logic.SpellCheck;
diff --git a/src/Forms/SplitLongLines.cs b/src/Forms/SplitLongLines.cs
index 60b92c9db..bc5e34e41 100644
--- a/src/Forms/SplitLongLines.cs
+++ b/src/Forms/SplitLongLines.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Drawing;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Forms;
 
diff --git a/src/Forms/Statistics.cs b/src/Forms/Statistics.cs
index d96c8feda..0ea200409 100644
--- a/src/Forms/Statistics.cs
+++ b/src/Forms/Statistics.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Drawing;
 using System.Text;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.SubtitleFormats;
 
diff --git a/src/Forms/SubStationAlphaProperties.cs b/src/Forms/SubStationAlphaProperties.cs
index 33010331b..4e6fbdaa6 100644
--- a/src/Forms/SubStationAlphaProperties.cs
+++ b/src/Forms/SubStationAlphaProperties.cs
@@ -4,6 +4,7 @@ using System.Drawing;
 using System.IO;
 using System.Text;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.SubtitleFormats;
 
diff --git a/src/Forms/SubStationAlphaStyles.cs b/src/Forms/SubStationAlphaStyles.cs
index 190b81677..d932ffe01 100644
--- a/src/Forms/SubStationAlphaStyles.cs
+++ b/src/Forms/SubStationAlphaStyles.cs
@@ -6,6 +6,7 @@ using System.Drawing.Text;
 using System.IO;
 using System.Text;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.SubtitleFormats;
 
diff --git a/src/Forms/TimedTextStyles.cs b/src/Forms/TimedTextStyles.cs
index 9d77dc2e5..b1d157a28 100644
--- a/src/Forms/TimedTextStyles.cs
+++ b/src/Forms/TimedTextStyles.cs
@@ -5,6 +5,7 @@ using System.Drawing.Text;
 using System.Text;
 using System.Windows.Forms;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.SubtitleFormats;
 
diff --git a/src/Forms/VisualSync.cs b/src/Forms/VisualSync.cs
index a0e97991a..7608a4e45 100644
--- a/src/Forms/VisualSync.cs
+++ b/src/Forms/VisualSync.cs
@@ -4,6 +4,7 @@ using System.Drawing;
 using System.IO;
 using System.Windows.Forms;
 using Nikse.SubtitleEdit.Controls;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.VideoPlayers;
 
diff --git a/src/Forms/VobSubEditCharacters.cs b/src/Forms/VobSubEditCharacters.cs
index f67f3e773..ca42e2c71 100644
--- a/src/Forms/VobSubEditCharacters.cs
+++ b/src/Forms/VobSubEditCharacters.cs
@@ -4,6 +4,7 @@ using System.Drawing;
 using System.IO;
 using System.Windows.Forms;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using Nikse.SubtitleEdit.Logic.Ocr.Binary;
 
diff --git a/src/Forms/VobSubOcrNewFolder.cs b/src/Forms/VobSubOcrNewFolder.cs
index 5a20d7d5c..23175c4e2 100644
--- a/src/Forms/VobSubOcrNewFolder.cs
+++ b/src/Forms/VobSubOcrNewFolder.cs
@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using System.Drawing;
 
diff --git a/src/Forms/Watermark.cs b/src/Forms/Watermark.cs
index ba49b057d..dc6da7895 100644
--- a/src/Forms/Watermark.cs
+++ b/src/Forms/Watermark.cs
@@ -2,6 +2,7 @@
 using System.Globalization;
 using System.Text;
 using System.Windows.Forms;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic;
 using System.Collections.Generic;
 using System.Drawing;
diff --git a/src/Logic/Dictionaries/NamesList.cs b/src/Logic/Dictionaries/NamesList.cs
index 94f897fef..0aca399fa 100644
--- a/src/Logic/Dictionaries/NamesList.cs
+++ b/src/Logic/Dictionaries/NamesList.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.Dictionaries
 {
diff --git a/src/Logic/Dictionaries/OcrFixReplaceList.cs b/src/Logic/Dictionaries/OcrFixReplaceList.cs
index b5ca6965a..0e6ecd076 100644
--- a/src/Logic/Dictionaries/OcrFixReplaceList.cs
+++ b/src/Logic/Dictionaries/OcrFixReplaceList.cs
@@ -5,6 +5,7 @@ using System.Text;
 using System.Text.RegularExpressions;
 using System.Windows.Forms;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.Dictionaries
 {
diff --git a/src/Logic/Forms/CheckForUpdatesHelper.cs b/src/Logic/Forms/CheckForUpdatesHelper.cs
index 9231f65f4..1b0d228ee 100644
--- a/src/Logic/Forms/CheckForUpdatesHelper.cs
+++ b/src/Logic/Forms/CheckForUpdatesHelper.cs
@@ -3,6 +3,7 @@ using System.Net;
 using System.Text;
 using System.Text.RegularExpressions;
 using System.Threading;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.Forms
 {
diff --git a/src/Logic/Forms/RemoveTextForHI.cs b/src/Logic/Forms/RemoveTextForHI.cs
index 03f4e2a7f..abc68a529 100644
--- a/src/Logic/Forms/RemoveTextForHI.cs
+++ b/src/Logic/Forms/RemoveTextForHI.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.Forms
 {
diff --git a/src/Logic/Forms/SplitLongLinesHelper.cs b/src/Logic/Forms/SplitLongLinesHelper.cs
index 2cfb38efa..a86c30b05 100644
--- a/src/Logic/Forms/SplitLongLinesHelper.cs
+++ b/src/Logic/Forms/SplitLongLinesHelper.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.Forms
 {
diff --git a/src/Logic/Mp4/Boxes/Stbl.cs b/src/Logic/Mp4/Boxes/Stbl.cs
index b593d0fbb..51ec71dae 100644
--- a/src/Logic/Mp4/Boxes/Stbl.cs
+++ b/src/Logic/Mp4/Boxes/Stbl.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using Nikse.SubtitleEdit.Core;
 using Nikse.SubtitleEdit.Logic.VobSub;
 using System.Text;
 
diff --git a/src/Logic/StripableText.cs b/src/Logic/StripableText.cs
index 7d4591a6d..167c7b540 100644
--- a/src/Logic/StripableText.cs
+++ b/src/Logic/StripableText.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic
 {
diff --git a/src/Logic/SubtitleFormats/AdvancedSubStationAlpha.cs b/src/Logic/SubtitleFormats/AdvancedSubStationAlpha.cs
index 57a715036..37287080a 100644
--- a/src/Logic/SubtitleFormats/AdvancedSubStationAlpha.cs
+++ b/src/Logic/SubtitleFormats/AdvancedSubStationAlpha.cs
@@ -4,6 +4,7 @@ using System.Drawing;
 using System.Globalization;
 using System.Text;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/AvidDvd.cs b/src/Logic/SubtitleFormats/AvidDvd.cs
index ae6e317bb..cc3b9c313 100644
--- a/src/Logic/SubtitleFormats/AvidDvd.cs
+++ b/src/Logic/SubtitleFormats/AvidDvd.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Cavena890.cs b/src/Logic/SubtitleFormats/Cavena890.cs
index 27dcecb1c..3508085e9 100644
--- a/src/Logic/SubtitleFormats/Cavena890.cs
+++ b/src/Logic/SubtitleFormats/Cavena890.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Csv.cs b/src/Logic/SubtitleFormats/Csv.cs
index fd98e5432..f64bb37de 100644
--- a/src/Logic/SubtitleFormats/Csv.cs
+++ b/src/Logic/SubtitleFormats/Csv.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Csv2.cs b/src/Logic/SubtitleFormats/Csv2.cs
index 12ea3f019..2158e4e64 100644
--- a/src/Logic/SubtitleFormats/Csv2.cs
+++ b/src/Logic/SubtitleFormats/Csv2.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Csv3.cs b/src/Logic/SubtitleFormats/Csv3.cs
index f7f703b61..3f6b63cfb 100644
--- a/src/Logic/SubtitleFormats/Csv3.cs
+++ b/src/Logic/SubtitleFormats/Csv3.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/DCSubtitle.cs b/src/Logic/SubtitleFormats/DCSubtitle.cs
index aea7a9922..d4fb6cb8a 100644
--- a/src/Logic/SubtitleFormats/DCSubtitle.cs
+++ b/src/Logic/SubtitleFormats/DCSubtitle.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.Text;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/DCinemaSmpte2007.cs b/src/Logic/SubtitleFormats/DCinemaSmpte2007.cs
index 7bd71cfa5..5092b477d 100644
--- a/src/Logic/SubtitleFormats/DCinemaSmpte2007.cs
+++ b/src/Logic/SubtitleFormats/DCinemaSmpte2007.cs
@@ -5,6 +5,7 @@ using System.IO.Compression;
 using System.Text;
 using System.Xml;
 using System.Xml.Schema;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/DCinemaSmpte2010.cs b/src/Logic/SubtitleFormats/DCinemaSmpte2010.cs
index 093495afa..90f090cf0 100644
--- a/src/Logic/SubtitleFormats/DCinemaSmpte2010.cs
+++ b/src/Logic/SubtitleFormats/DCinemaSmpte2010.cs
@@ -5,6 +5,7 @@ using System.IO.Compression;
 using System.Text;
 using System.Xml;
 using System.Xml.Schema;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Dost.cs b/src/Logic/SubtitleFormats/Dost.cs
index 356a5e04a..14aeaa998 100644
--- a/src/Logic/SubtitleFormats/Dost.cs
+++ b/src/Logic/SubtitleFormats/Dost.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/FlashXml.cs b/src/Logic/SubtitleFormats/FlashXml.cs
index 43410bcab..1cdf9ec94 100644
--- a/src/Logic/SubtitleFormats/FlashXml.cs
+++ b/src/Logic/SubtitleFormats/FlashXml.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Footage.cs b/src/Logic/SubtitleFormats/Footage.cs
index 5dd4bb97a..dac9058d8 100644
--- a/src/Logic/SubtitleFormats/Footage.cs
+++ b/src/Logic/SubtitleFormats/Footage.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Json.cs b/src/Logic/SubtitleFormats/Json.cs
index 38a82016a..53d926fae 100644
--- a/src/Logic/SubtitleFormats/Json.cs
+++ b/src/Logic/SubtitleFormats/Json.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/JsonType5.cs b/src/Logic/SubtitleFormats/JsonType5.cs
index 5ce220ee9..3361e3b79 100644
--- a/src/Logic/SubtitleFormats/JsonType5.cs
+++ b/src/Logic/SubtitleFormats/JsonType5.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/JsonType6.cs b/src/Logic/SubtitleFormats/JsonType6.cs
index 9ee5c6b08..7780f1d31 100644
--- a/src/Logic/SubtitleFormats/JsonType6.cs
+++ b/src/Logic/SubtitleFormats/JsonType6.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Lrc.cs b/src/Logic/SubtitleFormats/Lrc.cs
index 974ac7587..baac2a97d 100644
--- a/src/Logic/SubtitleFormats/Lrc.cs
+++ b/src/Logic/SubtitleFormats/Lrc.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/MPlayer2.cs b/src/Logic/SubtitleFormats/MPlayer2.cs
index 956fdff26..17ac006e4 100644
--- a/src/Logic/SubtitleFormats/MPlayer2.cs
+++ b/src/Logic/SubtitleFormats/MPlayer2.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/MicroDvd.cs b/src/Logic/SubtitleFormats/MicroDvd.cs
index d0a784f3b..347b57ce5 100644
--- a/src/Logic/SubtitleFormats/MicroDvd.cs
+++ b/src/Logic/SubtitleFormats/MicroDvd.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/ScenaristClosedCaptions.cs b/src/Logic/SubtitleFormats/ScenaristClosedCaptions.cs
index 53f3607f5..fb7f2e5b1 100644
--- a/src/Logic/SubtitleFormats/ScenaristClosedCaptions.cs
+++ b/src/Logic/SubtitleFormats/ScenaristClosedCaptions.cs
@@ -4,6 +4,7 @@ using System.Drawing;
 using System.Globalization;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SmilTimesheetData.cs b/src/Logic/SubtitleFormats/SmilTimesheetData.cs
index 38a32035d..6c72a08f3 100644
--- a/src/Logic/SubtitleFormats/SmilTimesheetData.cs
+++ b/src/Logic/SubtitleFormats/SmilTimesheetData.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Net;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SoftNiColonSub.cs b/src/Logic/SubtitleFormats/SoftNiColonSub.cs
index dff491675..aae763f47 100644
--- a/src/Logic/SubtitleFormats/SoftNiColonSub.cs
+++ b/src/Logic/SubtitleFormats/SoftNiColonSub.cs
@@ -1,7 +1,8 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SoftNiSub.cs b/src/Logic/SubtitleFormats/SoftNiSub.cs
index 5a21ffd7a..5aa5db1d3 100644
--- a/src/Logic/SubtitleFormats/SoftNiSub.cs
+++ b/src/Logic/SubtitleFormats/SoftNiSub.cs
@@ -1,7 +1,8 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Son.cs b/src/Logic/SubtitleFormats/Son.cs
index 602f13f6b..2fac01bde 100644
--- a/src/Logic/SubtitleFormats/Son.cs
+++ b/src/Logic/SubtitleFormats/Son.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SonicScenaristBitmaps.cs b/src/Logic/SubtitleFormats/SonicScenaristBitmaps.cs
index 9792d7ea7..bf7b8e8c8 100644
--- a/src/Logic/SubtitleFormats/SonicScenaristBitmaps.cs
+++ b/src/Logic/SubtitleFormats/SonicScenaristBitmaps.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Spruce.cs b/src/Logic/SubtitleFormats/Spruce.cs
index f096abd7e..d8e993205 100644
--- a/src/Logic/SubtitleFormats/Spruce.cs
+++ b/src/Logic/SubtitleFormats/Spruce.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SpruceWithSpace.cs b/src/Logic/SubtitleFormats/SpruceWithSpace.cs
index 684338500..f895f41e3 100644
--- a/src/Logic/SubtitleFormats/SpruceWithSpace.cs
+++ b/src/Logic/SubtitleFormats/SpruceWithSpace.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SubRip.cs b/src/Logic/SubtitleFormats/SubRip.cs
index c48e9a01e..284b37433 100644
--- a/src/Logic/SubtitleFormats/SubRip.cs
+++ b/src/Logic/SubtitleFormats/SubRip.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SubStationAlpha.cs b/src/Logic/SubtitleFormats/SubStationAlpha.cs
index 4c0f2c68e..b9ab49f91 100644
--- a/src/Logic/SubtitleFormats/SubStationAlpha.cs
+++ b/src/Logic/SubtitleFormats/SubStationAlpha.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Drawing;
 using System.Text;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SubViewer10.cs b/src/Logic/SubtitleFormats/SubViewer10.cs
index bbf8ccc02..952945a37 100644
--- a/src/Logic/SubtitleFormats/SubViewer10.cs
+++ b/src/Logic/SubtitleFormats/SubViewer10.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/SwiftInterchange2.cs b/src/Logic/SubtitleFormats/SwiftInterchange2.cs
index ae2e2eb39..0ca882eca 100644
--- a/src/Logic/SubtitleFormats/SwiftInterchange2.cs
+++ b/src/Logic/SubtitleFormats/SwiftInterchange2.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/TimedText.cs b/src/Logic/SubtitleFormats/TimedText.cs
index 4ee22b253..738a32911 100644
--- a/src/Logic/SubtitleFormats/TimedText.cs
+++ b/src/Logic/SubtitleFormats/TimedText.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/TimedText10.cs b/src/Logic/SubtitleFormats/TimedText10.cs
index 8168889eb..2db4d81b4 100644
--- a/src/Logic/SubtitleFormats/TimedText10.cs
+++ b/src/Logic/SubtitleFormats/TimedText10.cs
@@ -7,6 +7,7 @@ using System.Xml;
 //http://www.w3.org/TR/ttaf1-dfxp/
 //Timed Text Markup Language (TTML) 1.0
 //W3C Recommendation 18 November 2010
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/TmpegEncXml.cs b/src/Logic/SubtitleFormats/TmpegEncXml.cs
index c5580891a..47527e0a9 100644
--- a/src/Logic/SubtitleFormats/TmpegEncXml.cs
+++ b/src/Logic/SubtitleFormats/TmpegEncXml.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Xml;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UleadSubtitleFormat.cs b/src/Logic/SubtitleFormats/UleadSubtitleFormat.cs
index 054ff6cb6..22a1b8aad 100644
--- a/src/Logic/SubtitleFormats/UleadSubtitleFormat.cs
+++ b/src/Logic/SubtitleFormats/UleadSubtitleFormat.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Ultech130.cs b/src/Logic/SubtitleFormats/Ultech130.cs
index 4c7f2d1e4..75b436fbf 100644
--- a/src/Logic/SubtitleFormats/Ultech130.cs
+++ b/src/Logic/SubtitleFormats/Ultech130.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle10.cs b/src/Logic/SubtitleFormats/UnknownSubtitle10.cs
index b751785b3..b49b4815c 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle10.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle10.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle11.cs b/src/Logic/SubtitleFormats/UnknownSubtitle11.cs
index 4893070fd..9c8a7e463 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle11.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle11.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle32.cs b/src/Logic/SubtitleFormats/UnknownSubtitle32.cs
index fd99b578f..c0d4ece8c 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle32.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle32.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle42.cs b/src/Logic/SubtitleFormats/UnknownSubtitle42.cs
index ba4edea1c..af5962341 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle42.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle42.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle58.cs b/src/Logic/SubtitleFormats/UnknownSubtitle58.cs
index aa44edd99..97c19d978 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle58.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle58.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle68.cs b/src/Logic/SubtitleFormats/UnknownSubtitle68.cs
index dad977941..c7f0ee65a 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle68.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle68.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle70.cs b/src/Logic/SubtitleFormats/UnknownSubtitle70.cs
index a3581c111..48a3e1cf3 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle70.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle70.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle72.cs b/src/Logic/SubtitleFormats/UnknownSubtitle72.cs
index 493264ee9..c1acb552d 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle72.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle72.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle8.cs b/src/Logic/SubtitleFormats/UnknownSubtitle8.cs
index 47e8c1449..8e4606a15 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle8.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle8.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UnknownSubtitle9.cs b/src/Logic/SubtitleFormats/UnknownSubtitle9.cs
index 43d9feca6..e5fd3fbe3 100644
--- a/src/Logic/SubtitleFormats/UnknownSubtitle9.cs
+++ b/src/Logic/SubtitleFormats/UnknownSubtitle9.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/Utx.cs b/src/Logic/SubtitleFormats/Utx.cs
index 6511b193a..978bee2d8 100644
--- a/src/Logic/SubtitleFormats/Utx.cs
+++ b/src/Logic/SubtitleFormats/Utx.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/UtxFrames.cs b/src/Logic/SubtitleFormats/UtxFrames.cs
index 89ca4fb2e..c43136c5a 100644
--- a/src/Logic/SubtitleFormats/UtxFrames.cs
+++ b/src/Logic/SubtitleFormats/UtxFrames.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/WebVTT.cs b/src/Logic/SubtitleFormats/WebVTT.cs
index 2ebaf49a4..22cc217f0 100644
--- a/src/Logic/SubtitleFormats/WebVTT.cs
+++ b/src/Logic/SubtitleFormats/WebVTT.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/Logic/SubtitleFormats/WebVTTFileWithLineNumber.cs b/src/Logic/SubtitleFormats/WebVTTFileWithLineNumber.cs
index db2961e3e..64b40b230 100644
--- a/src/Logic/SubtitleFormats/WebVTTFileWithLineNumber.cs
+++ b/src/Logic/SubtitleFormats/WebVTTFileWithLineNumber.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.RegularExpressions;
+using Nikse.SubtitleEdit.Core;
 
 namespace Nikse.SubtitleEdit.Logic.SubtitleFormats
 {
diff --git a/src/SubtitleEdit.csproj b/src/SubtitleEdit.csproj
index 5ad3b97fb..cd1433107 100644
--- a/src/SubtitleEdit.csproj
+++ b/src/SubtitleEdit.csproj
@@ -88,6 +88,7 @@
     <Compile Include="Controls\AudioVisualizer.Designer.cs">
       <DependentUpon>AudioVisualizer.cs</DependentUpon>
     </Compile>
+    <Compile Include="Core\StringExtensions.cs" />
     <Compile Include="Forms\CheckForUpdates.cs">
       <SubType>Form</SubType>
     </Compile>
@@ -786,7 +787,6 @@
     <Compile Include="Logic\ColorChooser\ColorWheel.cs" />
     <Compile Include="Logic\Dictionaries\NamesList.cs" />
     <Compile Include="Logic\Dictionaries\OcrFixReplaceList.cs" />
-    <Compile Include="Logic\Extensions.cs" />
     <Compile Include="Core\FileUtil.cs" />
     <Compile Include="Logic\Forms\CheckForUpdatesHelper.cs" />
     <Compile Include="Logic\Forms\FixCommonErrorsHelper.cs" />