Syntax highlighting: Allow keyword groups without keywords to fix SD2-1354: Saving an empty keyword list using the highlighting editor causes the highlighting file to become invalid

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/branches/2.1@2539 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Libraries/ICSharpCode.TextEditor/Project/Resources/Mode.xsd

@@ -188,8 +188,9 @@
 	<!-- A grouping of keywords that sholuld be colored the same way -->
 	<xsd:complexType name="KeyWords">
 		<xsd:sequence>
+			<!-- allow groups with 0 keywords: this simplifies the syntax highlighting editor -->
 			<!-- A KeyWord -->
-			<xsd:element name="Key" type="Key" minOccurs="1" maxOccurs="unbounded">
+			<xsd:element name="Key" type="Key" minOccurs="0" maxOccurs="unbounded">
 			</xsd:element>
 		</xsd:sequence>
 		<!-- The name of the KeyWord group -->

src/Libraries/ICSharpCode.TextEditor/Project/Src/Gui/TextEditorControlBase.cs

@@ -624,7 +624,11 @@ namespace ICSharpCode.TextEditor
 			document.UndoStack.ClearAll();
 			document.BookmarkManager.Clear();
 			if (autoLoadHighlighting) {
-				document.HighlightingStrategy = HighlightingStrategyFactory.CreateHighlightingStrategyForFile(fileName);
+				try {
+					document.HighlightingStrategy = HighlightingStrategyFactory.CreateHighlightingStrategyForFile(fileName);
+				} catch (HighlightingDefinitionInvalidException ex) {
+					MessageBox.Show(ex.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+				}
 			}
 			
 			if (autodetectEncoding) {