Bug 23103 - Receiving unexpected MouseDown and MouseUp events on custom NSView
Summary: Receiving unexpected MouseDown and MouseUp events on custom NSView
Alias: None
Product: Xamarin.Mac
Classification: Desktop
Component: Other ()
Version: Master
Hardware: PC Mac OS
: Normal normal
Target Milestone: ---
Assignee: Chris Hamons
Depends on:
Reported: 2014-09-17 12:15 UTC by Travis Stutsman
Modified: 2014-12-04 15:05 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

Sample project (10.47 KB, application/zip)
2014-10-03 13:40 UTC, Travis Stutsman

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Description Travis Stutsman 2014-09-17 12:15:40 UTC
I have a class that inherits NSView and overrides the MouseUp method (MouseDown is also affected by this.)  With this NSView placed in a window I expect to only have this MouseUp method called when the mouse is within the bounds of my NSView, not when the mouse is in another part of the window.  Normally this is the case, but we've discovered a very strange bug.

If I left-click inside my NSView, then move to another part of this window and right-click then immediately left-click (as if to double-click, but right then left) another call is made to MouseUp on my NSView.  The location property of the event is well outside the bounds of my NSView.

I checked an older build of our application (with the runtime bundled) from February 28, 2014 and the same behavior exists, so this is not new.
Comment 1 Prashant manu 2014-09-29 02:42:30 UTC
Could you please provide us the test steps you followed. If possible please
attach a small complete project that demonstrates this behavior.

Also can you please add the logs from the following places?:
On XS IDE Log  Location: XS>Help> Open Log Directory> IDE.log file (with latest
Comment 2 Travis Stutsman 2014-10-03 13:40:07 UTC
Created attachment 8298 [details]
Sample project
Comment 3 Travis Stutsman 2014-10-03 13:47:43 UTC
In the sample application, if you left-click inside the red rectangle (the custom NSView) you get a "MouseDown" message in the console from the MouseDown override on the custom NSView.  This is expected behavior.  If you then proceed to right-click then left-click somewhere outside the red rectangle you will get another "MouseDown" message.  This is unexpected.
Comment 4 Chris Hamons 2014-12-04 15:05:38 UTC
While unfortunate behavior, this actually has nothing to do with Xamarin.Mac. We're exposing the underlying platform behavior perfectly.

I wrote a quick test app that did exactly what yours did:


And I got the same behavior. If i had to guess, It probably has to do with the way they do tracking loops. You could hit test inside your mouse down handler to see if it is in your Frame to detect this case.