[SOLVED] THUMBBUTTON does not work in Laz 64
lazarus / 34-Windows

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Xenno · 2025-07-15 03:05

My code below is to show thumb buttons on taskbar.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses ...
ShlObj ..// in classFTaskbarList: ITaskbarList;FTaskbarList3:
ITaskbarList3;   .. ..// in FormCreate or FormShowif
(CheckWin32Version(6, 1)) then begin  FTaskbarList :=
CreateComObject(CLSID_TaskbarList) as ITaskbarList; 
FTaskbarList.HrInit;  if (Supports(FTaskbarList, ITaskbarList3,
FTaskbarList3)) then begin    FTaskbarList3 :=
CreateComObject(CLSID_TaskbarList) as ITaskbarList3;  end;end;       
 .. procedure TFormMain.PrcThumbButtons;var  Buttons: array [1..2] of
THUMBBUTTON;  i: Integer;begin  Buttons[1].iId := 41;  if
(FilePrior1.Enabled) then begin    Buttons[1].dwFlags :=
THBF_ENABLED;    Buttons[1].iBitmap := 0;    
StrCopy(Buttons[1].szTip, 'Prior');  end else begin   
Buttons[1].dwFlags := THBF_DISABLED;    Buttons[1].iBitmap := 1;   
StrCopy(Buttons[1].szTip, '');  end;   Buttons[2].iId := 42;  if
(FileNext1.Enabled) then begin    Buttons[2].dwFlags := THBF_ENABLED; 
  Buttons[2].iBitmap := 2;    StrCopy(Buttons[2].szTip, 'Next');  end
else begin    Buttons[2].dwFlags := THBF_DISABLED;   
Buttons[2].iBitmap := 3;    StrCopy(Buttons[2].szTip, '');  end;  
{$IFDEF FPC}  if (FThumbButtonsFlag = '') then begin   
FTaskbarList3.ThumbBarSetImageList(Application.Handle,
ImageList2.Reference[0].Handle);   
FTaskbarList3.ThumbBarAddButtons(Application.Handle, Length(Buttons),
@Buttons);  end else   
FTaskbarList3.ThumbBarUpdateButtons(Application.Handle,
Length(Buttons), @Buttons);  {$ELSE}  if (FThumbButtonsFlag = '') then
begin    FTaskbarList3.ThumbBarSetImageList(Handle,
ImageList2.Handle);    FTaskbarList3.ThumbBarAddButtons(Handle,
Length(Buttons), @Buttons);  end else   
FTaskbarList3.ThumbBarUpdateButtons(Handle, Length(Buttons),
@Buttons);    {$ENDIF}   FThumbButtonsFlag := NewFlag;end;     
It works on Delphi 32-bits, Delphi 64-bits, and Lazarus 32-bits but it
fails on Lazarus 64-bits. I tried many things but still same result.
It looks like Laz 64 feed different size of THUMBBUTTON.

Does anyone have experience and solution?

TIA,

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ASerge · 2025-07-15 18:10

Quote from: Xenno on July 15, 2025, 05:05:55 amMy code below is to
show thumb buttons on taskbar.
Please make an example that can be compiled.
By the way in
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   if
(Supports(FTaskbarList, ITaskbarList3, FTaskbarList3)) then begin   
FTaskbarList3 := CreateComObject(CLSID_TaskbarList) as
ITaskbarList3;why are you calling CreateComObject again? FTaskbarList3
has already been initialized with the Supports function.

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Xenno · 2025-07-16 06:52

Quote from: ASerge on July 15, 2025, 08:10:40 pmPlease make an example
that can be compiled.
Sure, attached.
32 bits in Laz 3.8 (OK)
64 bits in Laz 4.0 (not OK)

Quote from: ASerge on July 15, 2025, 08:10:40 pmwhy are you calling
CreateComObject again? FTaskbarList3 has already been initialized with
the Supports function.

You are right. I was modifying the code in trying to find solution.
Please refer to the attached code,

TIA,

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ASerge · 2025-07-16 17:51

Quote from: Xenno on July 16, 2025, 08:52:47 amSure, attached.
32 bits in Laz 3.8 (OK)
64 bits in Laz 4.0 (not OK)
Yes, it won't work in 64-bit.
Workaround: copy the definition of "THUMBBUTTON" and delete "packed"
from it.
These are the new last lines of the example:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   if
FThumbButtonsFlag = '' then  begin   
FTaskbarList3.ThumbBarSetImageList(Application.Handle,
ImageList1.Reference[0].Handle);   
FTaskbarList3.ThumbBarAddButtons(Application.Handle, Length(Buttons),
Pointer(@Buttons[1]));  end  else   
FTaskbarList3.ThumbBarUpdateButtons(Application.Handle,
Length(Buttons), Pointer(@Buttons[1]));
QuoteYou are right. I was modifying the code in trying to find
solution. Please refer to the attached code,
Better:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  
FTaskbarList := CreateComObject(CLSID_TaskbarList) as ITaskbarList; 
FTaskbarList.HrInit;  if not Supports(FTaskbarList, ITaskbarList3,
FTaskbarList3) then    FTaskbarList3 := nil;  FThumbButtonsFlag := '';
Please add the issue to the FPC bug list.

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Xenno · 2025-07-16 18:50

Confirmed. This workaround solves the issue.
The iId values are also correct in WMSYSCOMMAND WM_COMMAND.

Note: @Buttons also works instead of Pointer(@Buttons[1])

Thank you very much, ASerge.

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ASerge · 2025-07-16 19:03

Quote from: Xenno on July 16, 2025, 08:50:12 pmNote: @Buttons also
works instead of Pointer(@Buttons[1])
I always test with {$T+} (in Project/Project Options.../Compiler
Options/Parsing)
In this case, the compiler throws an error:
Error: Incompatible type for arg no. 3: Got "^Array[1..2] Of
THUMBBUTTON", expected "LPTHUMBBUTTON"

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ASerge · 2025-07-16 19:22

Added issue 41333 to the buglist.

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Xenno · 2025-07-17 05:32

Thank you again, ASerge.

If anyone needs to implement THUMBBUTTON further, allow me to share
code.

1. Add a private procedure to handle THUMBBUTTON when clicked and
implement it, for example:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   ... 
private    procedure PrcThumbButtonClick(PrmId: Integer);  
... procedure TFormMain.PrcThumbButtonClick(PrmId: Integer);begin 
ShowMessage('ID: ' + IntToStr(PrmId)); // replace this with yoursend;
   
2. Add form's Windows message handler in public part of form class and
implement it, for example:     
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   ... 
public    function FncAppWndCallback(Ahwnd: HWND; uMsg: UINT; wParam:
WParam;       lParam: LParam): LRESULT;     ... function
TFormMain.FncAppWndCallback(Ahwnd: HWND; uMsg: UINT; wParam: WParam; 
lParam: LParam): LRESULT;begin  case uMsg of    WM_COMMAND: begin    
if (HIWORD(WParam) = THBN_CLICKED) then       
PrcThumbButtonClick(LOWORD(WParam));    end;  end;  Result :=
CallWindowProc(PrevAppWndProc, Ahwnd, uMsg, WParam, LParam);end;
3. Add application's Windows message handler in unit's implementation
section:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var 
PrevAppWndProc: WNDPROC; function AppWndCallback(Ahwnd: HWND; uMsg:
UINT; wParam: WParam;  lParam: LParam): LRESULT; stdcall;begin  Result
:= FormMain.FncAppWndCallback(Ahwnd, uMsg, WParam, LParam);end;
4. Insert code in Form show:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
PrevAppWndProc := Windows.WNDPROC(SetWindowLongPtr(Application.Handle,
GWL_WNDPROC, PtrUInt(@AppWndCallback))); 

Done. The application is ready to respond when a thumb button is
clicked.


Cheers,

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ASerge · 2025-07-17 15:33

Quote from: Xenno on July 17, 2025, 07:32:18 amIf anyone needs to
implement THUMBBUTTON further, allow me to share code.
Safer:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses
Windows, Messages, CommCtrl, ComObj;//...function AppSubClassProc(Wnd:
HWND; Msg: UINT; WParam: WPARAM; LParam: LPARAM;  uISubClass:
UINT_PTR; dwRefData: DWORD_PTR): LRESULT; stdcall;var  Self: TFormMain
absolute dwRefData;begin  if (Msg = WM_COMMAND) and (HIWORD(WParam) =
THBN_CLICKED) then    Self.PrcThumbButtonClick(LOWORD(WParam)); 
Result := DefSubclassProc(Wnd, Msg, WParam, LParam);end; procedure
TFormMain.FormShow(Sender: TObject);begin 
SetWindowSubclass(Application.Handle, @AppSubClassProc, 1,
DWORD_PTR(Self));end;