From d82273381f1f34c70bc5854686ac7e7d4ccc8ef4 Mon Sep 17 00:00:00 2001
From: wp_xxyyzz <wp_xxyyzz@8e941d3f-bd1b-0410-a28a-d453659cc2b4>
Date: Tue, 19 Jul 2022 22:07:26 +0000
Subject: [PATCH] TvPlanIt: Fix TVpResourceCombo crashing when used in a frame
 ("... has no parent")

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@8353 8e941d3f-bd1b-0410-a28a-d453659cc2b4
---
 components/tvplanit/source/vpbaseds.pas | 37 +++++++++++++++++++------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/components/tvplanit/source/vpbaseds.pas b/components/tvplanit/source/vpbaseds.pas
index f470b4653..ed498db2c 100644
--- a/components/tvplanit/source/vpbaseds.pas
+++ b/components/tvplanit/source/vpbaseds.pas
@@ -150,12 +150,16 @@ type
   end;
 
   TVpResourceCombo = class(TCustomComboBox)
-    protected {private}
+    private
       FDataStore: TVpCustomDataStore;
+      FPendingDatastore: TVpCustomDatastore;
+      procedure InternalSetDatastore(const Value: TVpCustomDatastore);
+    protected {private}
       {internal variables}
       rcLoading: Boolean;
       OldItemIndex: Integer;
       FResourceUpdateStyle: TVpResourceUpdate;
+      procedure CreateHandle; override;
 
       procedure VpDataStoreChanged(var Msg: {$IFDEF DELPHI}TMessage{$ELSE}TLMessage{$ENDIF}); message Vp_DataStoreChanged;
       procedure SetDataStore(const Value: TVpCustomDataStore);
@@ -1256,24 +1260,39 @@ begin
     end;
   end;
 end;
-{=====}
+
+procedure TVpResourceCombo.CreateHandle;
+begin
+  inherited;
+  if FPendingDatastore <> nil then
+  begin
+    InternalSetDatastore(FPendingDatastore);
+    FPendingDatastore := nil;
+  end;
+end;
 
 procedure TVpResourceCombo.SetDataStore(const Value: TVpCustomDataStore);
+begin
+  if HandleAllocated then
+    InternalSetDatastore(Value)
+  else
+    // Delay linking of the datastore until the Handle has been created.
+    FPendingDatastore := Value;
+end;
+
+procedure TVpResourceCombo.InternalSetDatastore(const Value: TVpCustomDatastore);
 begin
   if FDataStore <> Value then begin
-    if (Assigned (FDataStore)) and
-       (not (csDesigning in ComponentState)) then
-      FDataStore.DeregisterWatcher (Handle);
+    if Assigned (FDataStore) and not (csDesigning in ComponentState) then
+      FDataStore.DeregisterWatcher(Handle);
     FDataStore := Value;
-    if (Assigned (FDataStore)) and
-       (not (csDesigning in ComponentState)) then
-      FDataStore.RegisterWatcher (Handle);
+    if Assigned (FDataStore) and not (csDesigning in ComponentState) then
+      FDataStore.RegisterWatcher(Handle);
     if not (csDesigning in ComponentState) then
       LoadItems;
     Invalidate;
   end;
 end;
-{=====}