Why do I get the "busy" mouse cursor?

[vefatica]

I'm revisiting an old problem and since I can't figure it out, I'm asking the experts.

My shell (TCC) misbehaves in that it makes GetConsoleWindow() the foreground window after displaying a GUI dialog (I would rather WindowsTerminal become the foreground window). I work around that (in a plugin DLL) with a WinEventHook targeting EVENT_SYSTEM_FOREGROUND. The SetForegroundWindow() is successful and WT has keyboard input focus, but I get the "busy" mouse cursor (spinning blue wheel) which persists until I use the mouse (which includes using the snipping tool). I can get rid of it with a mouse-click kludge. My hook process looks like this (including a bit of debugging output).

// EVENT_SYSTEM_FOREGROUND
VOID CALLBACK hookproc2(HWINEVENTHOOK hWinEventHook, DWORD event, HWND hwnd, LONG idObject, LONG idChild, DWORD dwEventThread, DWORD dwmsEventTime)
{
	if ( hwnd == g.hWndConsole ) // PseudoConsoleWindow
	{
		BOOL b = SetForegroundWindow(g.hWndCascadia); // succeeds but still get busy pointer, why?
		if ( b ) Printf(L"SetForegroundWindow was successful\r\n");
		if ( MouseInWT() )
		{
			ClickMouse(); // left down/up; this gets rid of the "busy" mouse pointer
		}
	}
}

When I open /close TCC's options dialog (class #32770) while monitoring the foreground window, I see this (and the busy cursor). Note that if the mouse pointer is not in WT when I dismiss the dialog, I do not get the busy cursor and all's well.

v:\> thread option & do forever ( delay 1 & echo %@fgwin[C] )
"#32770"
"#32770"
"#32770"
SetForegroundWindow was successful
"CASCADIA_HOSTING_WINDOW_CLASS"
"CASCADIA_HOSTING_WINDOW_CLASS"
"CASCADIA_HOSTING_WINDOW_CLASS"

Any ideas on why I get the busy cursor and how to avoid it? Thanks!