Add IOutputPad.GetOrCreateCategory()

src/Main/Base/Project/Src/Gui/Pads/CompilerMessageView/CompilerMessageView.cs

@@ -56,6 +56,22 @@ namespace ICSharpCode.SharpDevelop.Gui
 			return cat;
 		}
 
+		IOutputCategory IOutputPad.GetOrCreateCategory(string displayName)
+		{
+			return SD.MainThread.InvokeIfRequired(() => GetOrCreateCategory(displayName));
+		}
+		
+		IOutputCategory GetOrCreateCategory(string displayName)
+		{
+			foreach (var cat in messageCategories) {
+				if (cat.DisplayCategory == displayName)
+					return cat;
+			}
+			var newcat = new MessageViewCategory(displayName, displayName);
+			AddCategory(newcat);
+			return newcat;
+		}
+		
 		void IOutputPad.RemoveCategory(IOutputCategory category)
 		{
 			throw new NotImplementedException();

src/Main/Base/Project/Workbench/IOutputPad.cs

@@ -38,8 +38,16 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		/// <summary>
 		/// Creates a new output category.
 		/// </summary>
+		/// <param name="displayName">The title of the category. This is parsed using StringParser and shown to the user.</param>
 		IOutputCategory CreateCategory(string displayName);
 		
+		/// <summary>
+		/// Gets an output category, or creates a new output category if no category with the given
+		/// title already exists.
+		/// </summary>
+		/// <param name="displayName">The title of the category. This is parsed using StringParser and shown to the user.</param>
+		IOutputCategory GetOrCreateCategory(string displayName);
+		
 		/// <summary>
 		/// Removes an existing output category.
 		/// </summary>
@@ -65,6 +73,8 @@ namespace ICSharpCode.SharpDevelop.Workbench
 	{
 		/// <summary>
 		/// Gets the display name of this category.
+		/// May contain StringParser-tags ($res) for localization; these will be replaced
+		/// by the UI showing the display name.
 		/// </summary>
 		string DisplayName { get; }