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

My logic for not display a context menu is a bit simplistic, as it
doesn't work for a double right-click on a checkbox - the second
mouse-down does not generate a WM_CONTEXTMENU event.

Best Regards,
Richard B.


On 02/07/2012 20:20, Richard wrote:
>  
> 
> 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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