Mouse state with menu items overlapping control

Question

Hi,
I have an issue with retrieving the mouse location using GetGraphCoordsFromPoint...
I am using the return status of GetGraphCoordsFromPoint to determine if the mouse cursor is above the plot area of my graph control (1) or not (0) in order to switch between the mouse styles (VAL_DEFAULT_CURSOR versus VAL_CROSS_HAIR_CURSOR).
It works in most cases...
On top of the panel there is a menu bar, located below is the xy graph. Now, if the mouse opens a menu and is over the menu (and also over the graph) the mouse style depends on mouse history:
If the mouse has always been located over the menu, it is not recognized by GetGraphCoordsFromPoint to be loacted over the graph - which is what I would like to see, in this case the cursor style still is the default style.
Now, if the mouse leaves the menu for a short distance, the menu does not disappear (only if the mouse is at a larger distance) and acccordingly GetGraphCoordsFromPoint realizes that the mouse is over the graph. This is correct and as expected, too.(the mouse style is changed to a cross hair then)
Now, if I move the mouse back over the menu, this is not recognized by GetGraphCoordsFromPoint, unfortunately, and the mouse style is not switched back to default.
Am I missing something, or is there a way to correct this behavior? Having different mouse styles over a menu is confusing for the user and I'd like to avoid that, of course
Thanks....
Solved!
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Answer 1

Hi Wolfgang,
There isn't a very good way to get around this problem. As you've found, panel move events are sent to the panel's callback even while a menu is being tracked, and when you change the mouse cursor this this also impacts any menu that might be active at the time.
If you don't mind the cursor not changing at all while the menu is active, even if the user moves over the graph, then there is a possible strategy you can pursue to remedy the situation. It consists of trying to detect when a menu is active so that you don't try to change the cursor while the menu is active. Unfortunately, this is easier said than done. Although it's straightforward to be notified whenever a new menu becomes active (via a menu dimmer callback) there is no good way to be notified when the menu goes away. And there are multiple ways in which it can go away. So it it not possible for you to set an internal flag that tracks when the menu is active.
However, it is possible to find out whether the menu is active at the time that you receive the panel move event (or in the timer tick event, although I'm not completely sure why you are also using a timer). You can't do it with the CVI UI library, but you can, using the Windows SDK, in a somewhat round-about way.
The idea is to find out which window is the topmost window. And if it is not the panel window, then you should be able to assume that a menu is active and thus refrain from changing the cursor. Note that you also have to make sure that the active window belongs to your process, since there could be any number of other windows that could be the "topmost" window at any one time. But if it belongs to your process and it is not your panel, then we can assume that it's the menu.
I did a quick test with the following code and it seems to work, although you might want to test it more thoroughly than I did:
topHwnd = GetTopWindow (NULL);
GetWindowModuleFileName (topHwnd, topHwndModule, MAX_PATHNAME_LEN);
GetPanelAttribute (panel, ATTR_SYSTEM_WINDOW_HANDLE, (intptr_t *)&panelHwnd);
GetWindowModuleFileName (panelHwnd, panelHwndModule, MAX_PATHNAME_LEN);
if (!strcmp (topHwndModule, panelHwndModule) && panelHwnd != topHwnd)
    return 0; // don't change the cursor unless the panel really is on top
Good luck,
Luis