Win32 SetCursor from other thread (Wait Cursor)

Question

As soon as my application starts to decode a bitmap, i need to update two static text labels to show current progress. Updating them for every decoded pixel would be too overkill so I decided to make every update inside a timer every 150ms.
This obviously implies the use of a worker thread that leaves the main UI thread able to process WM_TIMER messages thus updating these two textlabels, and invalidate the possibility of just surrounding my work code in two SetCursor functions.
I googled a bit and found that handling WM_SETCURSOR could do the trick, and so I tested it this way :
case WM_SETCURSOR:
if (DecodingThreadRunning) SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_WAIT)));
else SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_ARROW)));
break;
Somehow the call gets executed with no errors but the cursor remain the same.
I also tried to surrond the working thread with the AttachThreadInput function but still no luck :
HWND hWnd = GetForegroundWindow();
DWORD foregroundThreadID = GetWindowThreadProcessId(hWnd, 0);
DWORD currentThreadID = GetCurrentThreadId();
AttachThreadInput(foregroundThreadID, currentThreadID, TRUE);
SetCursor(LoadCursor(NULL, MAKEINTRESOURCE(IDC_WAIT)));
//Do the work
AttachThreadInput(foregroundThreadID, currentThreadID, FALSE);
Honestly I feel lost since i'm not even sure that the IDC_WAIT cursor was supposed to be used in this case, since the main GUI remains actually usable and stable (although few option gets disabled)
Thanks in advance for any help
PS: Running an update every nth pixel would not be as stable and fancy looking as the more accurate update of a timer
PPS: That's it I'm a retard.    I forgot to return TRUE from WM_SETCURSOR.
I'll change the core of the question then : is the wait cursor supposed to be used in this case ? why attachthreadinput does not work ? Does it needs the thread to have a message queue ?

Answer 1

Somehow the call gets executed with no errors but the cursor remain the same.
Set a breakpointer to check if SetCursor method is reached.
if (DecodingThreadRunning)
And how do you determine your thread is running? Do you use WaitForSingleObject method? We need some more information to reproduce this issue.
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