Fix #580: EventHandler names suggested by code completion should include the variable name/expression.

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngine.cs

@@ -886,7 +886,7 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 									string parameterDefinition = AddDelegateHandlers(
 										wrapper,
 										delegateType,
-										optDelegateName: GuessEventHandlerMethodName(curTokenIndex)
+										optDelegateName: GuessEventHandlerMethodName(curTokenIndex, (currentType == null) ? null : currentType.Name)
 									);
 								}
 
@@ -2584,10 +2584,49 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 			}
 		}
 
-		public string GuessEventHandlerMethodName(int tokenIndex)
+		public string GuessEventHandlerMethodName(int tokenIndex, string surroundingTypeName)
 		{
+			var names = new List<string>();
+			
+			string eventName = GetPreviousToken(ref tokenIndex, false);
 			string result = GetPreviousToken(ref tokenIndex, false);
-			return "Handle" + result;
+			if (result != ".") {
+				if (surroundingTypeName == null) {
+					eventName = "Handle" + eventName;
+				} else {
+					names.Add(surroundingTypeName);
+				}
+			}
+			while (result == ".") {
+				result = GetPreviousToken(ref tokenIndex, false);
+				if (result == "this") {
+					if (names.Count == 0) {
+						if (surroundingTypeName == null) {
+							eventName = "Handle" + eventName;
+						} else {
+							names.Add(surroundingTypeName);
+						}
+					}
+				} else if (result != null) {
+					string trimmedName = result.Trim();
+					if (trimmedName.Length == 0) {
+						break;
+					}
+					names.Insert(0, trimmedName);
+				}
+				result = GetPreviousToken(ref tokenIndex, false);
+			}
+			if (!string.IsNullOrEmpty(eventName)) {
+				names.Add(eventName);
+			}
+			result = String.Join("_", names.ToArray());
+			foreach (char ch in result) {
+				if (!char.IsLetterOrDigit(ch) && ch != '_') {
+					result = "";
+					break;
+				}
+			}
+			return result;
 		}
 
 		bool MatchDelegate(IType delegateType, IMethod method)