richmemo: saving fRTF on DestroyHandle event to follow LCL requirements about properties being available with/without window Handle

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@5068 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/richmemo/richmemo.pas

@@ -272,6 +272,7 @@ type
     function GetRTF: string; virtual;
     procedure SetRTF(const AValue: string); virtual;
     procedure UpdateRichMemo; override;
+    procedure DestroyHandle; override;
   published
     property Align;
     property Alignment;
@@ -573,6 +574,12 @@ begin
   if fRTF<>'' then SetRTF(fRTF);
 end;
 
+procedure TRichMemo.DestroyHandle;
+begin
+  fRTF:=GetRTF;
+  inherited DestroyHandle;
+end;
+
 { TCustomRichMemo }
 
 procedure TCustomRichMemo.SetHideSelection(AValue: Boolean);