Fixed SD2-711: Clear all bookmarks menu option selected when bookmarks pad not visible

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/branches/2.0@1195 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Main/Base/Project/Src/TextEditor/Bookmarks/Pad/BookmarkPad.cs

@@ -29,6 +29,9 @@ namespace ICSharpCode.SharpDevelop.Bookmarks
 		
 		public static BookmarkPad Instance {
 			get {
+				if (instance == null) {
+					WorkbenchSingleton.Workbench.GetPad(typeof(BookmarkPad)).CreatePad();
+				}
 				return instance;
 			}
 		}