[UniSoft]

1. Create new Windows VCL Application – Delphi
2. Drop on form TsSkinManager, select any skin
3. Drop TsSaveDialog, and button in onclick: sSaveDialog.Execute;
4. Run under debugger
When you click on any button (Ok, Cancel) in dialog, you get exception “Access violation” and cannot continue.
But if you click on cross then the dialog closing without exception.

it happens here: (actually inside System.Classes.StdWndProc(0,0,0,0);)

function TacMainWnd.CallPrevWndProc(const Handle: hwnd; const Msg: longint; const WParam: WPARAM; var LParam: LPARAM): LRESULT;
begin
  ---
  else
    if Assigned(OldProc) then
      try // this try-except swallow exception, so without debugger can't see it
        Result := CallWindowProc(OldProc, Handle, Msg, WParam, LParam) // <<<< after call this function
      except
        Result := 0;
      end
    else
      Result := 0;
end;

you can add a breakpoint

function TacMainWnd.CallPrevWndProc(const Handle: hwnd; const Msg: longint; const WParam: WPARAM; var LParam: LPARAM): LRESULT;
begin
  ---
  else
    if Assigned(OldProc) then
      try // this try-except swallow exception, so without debugger can't see it

        // >>>>>> add this <<<<<<<
        if Message.Msg = 1046 then
          Result := 0; // <<<< put breakpoint on this line, so the next call of CallWindowProc() will give an exception

        Result := CallWindowProc(OldProc, Handle, Msg, WParam, LParam) // <<<< after call this function
      except
        Result := 0;
      end
    else
      Result := 0;
end;

Still didn’t figure out what is message 1046

[Support]

Hello!
I can’t repeat it unfortunately, maybe some another condition is required..
Is it possible to make a demo with this error?
Which Delphi version do you use?

[UniSoft]

Windows 7
RAD 10.4 with last 2 updates

By the way, bug with GripPos is not fixed

function TsStatusBar.GripPos: TPoint;
begin
  if FCommonData.SkinManager <> nil then
    with FCommonData.SkinManager, SkinData.CommonSkinData do
      if IsValidImgIndex(GripRightBottom) then begin
        Result := Point(Width - ma[GripRightBottom].Width - BorderWidth, Height - ma[GripRightBottom].Height - BorderWidth);
        Exit;
      end;

  Result := Point(Width - GetSystemMetrics(SM_CXSIZEFRAME), Height - GetSystemMetrics(SM_CYSIZEFRAME));
end;

[UniSoft]

I tried to make demo, but it is crashed only under debugger
First I commented try..except
then compile release version…
if I run it from rad studio in debugger, then it crash…
If I open exe in any debugger (OllyDbg, x64dbg, …) they catch Access Violation…

function TacMainWnd.CallPrevWndProc(const Handle: hwnd; const Msg: longint; const WParam: WPARAM; var LParam: LPARAM): LRESULT;
var
  M: TMessage;
begin
  if Assigned(OldWndProc) then begin
    M.Msg := Msg;
    M.WParam := WParam;
    M.LParam := LParam;
    M.Result := 0;
    OldWndProc(M);
    Result := M.Result;
    LParam := M.LParam;
  end
  else
    if Assigned(OldProc) then
      //try
        Result := CallWindowProc(OldProc, Handle, Msg, WParam, LParam)
      //except
      //  Result := 0;
      //end
    else
      Result := 0;
end;

Alternate link to demo (with compiled exe)
__https__://mega.nz/file/xO5BiQpJ#MRE7uX5rWFFbe1gKJ8snE1Fruj8XJiXfuKUqxXNcP_g

Attachments:

You must be logged in to view attached files.

[UniSoft]

I found problem…
“AnVir Task Manager” adds an icon to the tool bar of open/save dialog and it is the reason why it crash.
But anyway strange, if to disable skinning, then there is no crash.
BTW, message 1046 – probably TB_DELETEBUTTON
shit.. and I had this problem before, just forgot :(.

[UniSoft]

This helps to solve that crash
comment WM_DESTROY
What for need to process both WM_DESTROY and WM_NCDESTROY?
WM_NCDESTROY is the last one, so should be enough.

procedure TacDialogWnd.acWndProc(var Message: TMessage);
var
  PS: TPaintStruct;
  X, Y, i: integer;
  cR, rClient: TRect;
begin
  case Message.Msg of
    {WM_DESTROY,} WM_NCDESTROY: begin
      if SkinData.FCacheBmp <> nil then
        SkinData.FCacheBmp.Assign(nil);
  ...
    end;

[UniSoft]

just some explain, what doing AnVir, now you can see why it cause crash

  case Msg of
  WM_DESTROY, WM_CLOSE: 
    begin
      // here is the problem!!! 
      // this call should be after clean up, not before
      CallWindowProc(PrevWndFunc, ...); // !!!

     // After called Destructor all bottom crap can cause an error
	  
      // this called on init time, then add custom buttons
      //  so btncount cotaint number of buttons in toolbat before add new buttons
      //btncount := SendMessageA(Handle, TB_BUTTONCOUNT, 0, 0); //
	  
      // restore previous WndProc
      SetWindowLong(Handle, GWLP_WNDPROC, PrevWndFunc);
	  
      // delete custom buttons
      SendMessageA(Handle, TB_DELETEBUTTON, btncount + 1, 0);
      SendMessageA(Handle, TB_DELETEBUTTON, btncount    , 0);
    end;
  end;

[Support]

Hello!
I have found a potential reason of the problem there.
Plz, wait a new release and check it (v16.12).
Or, I can send you a patched unit if you have sources of the package.

[UniSoft]

Up to you
If you need I can check it before release…

[UniSoft]

Hello!
I Checked v16.12
still have the same crash… 🙁

I can clearly see in the debugger what exactly is going on…
Look

1. AC sets the new Window Pointer

   InitializeACWnd
      OldProc := Pointer(GetWindowLong(CtrlHandle, GWL_WNDPROC));
      NewWndProcInstance := {$IFDEF DELPHI6UP}Classes.{$ENDIF}MakeObjectInstance(acWndProc);
      SetWindowLong(CtrlHandle, GWL_WNDPROC, LONG_PTR(NewWndProcInstance));

2. Now AnVir do the same (and saves OldProc which is actually already = NewWndProcInstance)
3. Closing Dialog
4. Get message WM_DESTROY (Notice! it doesn’t get WM_CLOSE, at least I don’t see it in WinSpy)
Now the AnVir first pass processing to the old wndProc (what is actually = NewWndProcInstance!)
on process of WM_DESTROY – AC restores original OldProc, after that AC deletes NewWndProcInstance
FreeObjectInstance(ListSW.NewWndProcInstance);

   procedure UninitializeACWnd(...
        if Assigned(ListSW.OldProc) then begin
          SetWindowLong(Handle, GWL_WNDPROC, LONG_PTR(ListSW.OldProc));
          ListSW.OldProc := nil;
          if Assigned(ListSW.NewWndProcInstance) then begin
            {$IFDEF DELPHI6UP}Classes.{$ENDIF}FreeObjectInstance(ListSW.NewWndProcInstance);
            ListSW.NewWndProcInstance := nil;
          end;
        end

5. process returns back to the AnVir, where this shit also thinking that restores old WndProc
SetWindowLong(Handle, GWLP_WNDPROC, PrevWndFunc);
BUT! it is a pointer to already deleted NewWndProcInstance
And follow send the messages

        SendMessageA(Handle, TB_DELETEBUTTON, btncount + 1, 0);
         SendMessageA(Handle, TB_DELETEBUTTON, btncount    , 0);

That is the actually reason!

—
BUG with StatusBar still not fixed as well 🙁
to see it:
1. Launch ASkinDemo.exe
2. Select skin: Standard theme
3. Move cursor over StatusBar
Fixed code is few posts up…

[Support]

Thanks for researching, I will check how to avoid this situation.
And StatusBar in standard non-skinned mode will be fixed in the nearest release.

[Author]

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