Right-click on a checkbox in a CCheckListViewCtrl results in two WM_CONTEXTMENU messages...

I've noticed that a right-click on a checkbox in a CCheckListViewCtrl
results in two WM_CONTEXTMENU (also NM_RCLICK) messages being sent - one
for the mouse down (incorrect), and another for the mouse up (expected).
The point parameter indicating the cursor location, is incorrect for the
second message.

This appears to be a bug in Windows/Common Controls, as opposed to WTL,
as the MSDN docs states WM_CONTEXTMENU is generated after WM_RBUTTONUP
or WM_NCRBUTTONUP message, or when the user types SHIFT+F10 or when the
user presses and releases the VK_APPS key.

I only noticed this issue when I wrapped my call to TrackPopupMenuEx()
in a MFC style VERIFY() macro, which indicated it was failing on the
second WM_CONTEXTMENU message.

The odd thing is that when you call TrackPopupMenuEx() in the
WM_CONTEXTMENU handler function, the WM_CONTEXTMENU handler function is
called again BEFORE the WM_CONTEXTMENU handler function exits, and so
the second call to TrackPopupMenuEx() fails (no doubt due to the menu
already being displayed).

As a right-click changes the state of the checkbox, I thought about not
showing the context menu if the click occurs over the checkbox, and
initially put the following at the beginning of my handler:

UINT flags;
HitTest(point, &flags);
if (flags & LVHT_ONITEMSTATEICON)
	return;

Unfortunately, when the control is in detail mode, HitTest always
returns LVHT_NOWHERE.

My current solution is to ignore the WM_CONTEXTMENU on mousedown, but
still display the context menu:

// Check this is mouse event and mouse right button is pressed or not
if (	!((point.x == -1) && (point.y == -1))	&&
	(GetKeyState(VK_RBUTTON) & VKEY_DOWN))
		return; // RButton pressed"));

If you don't want to display the context menu, just replace the above with:

static bool bRightClickOnCheckbox = false;
if (bRightClickOnCheckbox) {
	bRightClickOnCheckbox = false;
	return;
}
// Check this is mouse event and mouse right button is pressed or not
if (	!((point.x == -1) && (point.y == -1))	&&
	(GetKeyState(VK_RBUTTON) & VKEY_DOWN)) {
	bRightClickOnCheckbox = true;
	return; // RButton pressed"));
}


Something like this could be added to
CCheckListViewCtrl::OnContextMenu(), as a workaround to the bug, with
the bRightClickOnCheckbox as a template parameter, to control whether
the menu is displayed.

Best Regards,
Richard B.



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