Find the topmost window under a mouse cursor

Anthony Petrov anthony.petrov at
Tue Mar 27 03:23:21 PDT 2012

On 3/27/2012 2:19 PM, Dmitry Cherepanov wrote:
>> I suggest to track the MouseIsOver state with a boolean flag per 
>> window, and send a synthetic Entered event upon receiving any other 
>> mouse event (Moved, Clicked, etc.)
> We should probably synthesize such mouse enter/exit events upon changing 
> window's bounds. Synthesizing the mouse enter/exit event upon receiving 
> any other mouse event wouldn't changes the mouse cursor until the user 
> performs any mouse action.

Is this exact behavior specified anywhere (i.e. that the cursor must be 
updated as soon as a component appears under the mouse even if the mouse 
holds still)? If not, I'd just state that the behavior is platform-specific.

best regards,

> Thanks,
> Dmitry
>> if the flag indicates we haven't yet sent an Entered event for this 
>> window. The flag should be set/reset in the Entered/Exited mouse 
>> handlers.
>> We use this approach in FX and everyone seems to be happy about that.
>> -- 
>> best regards,
>> Anthony
>> On 3/27/2012 12:08 PM, Alexander Scherbatiy wrote:
>>> Hello,
>>> Does the Mac OS X contains a method that allows to find the topmost 
>>> window under a mouse cursor?
>>> There is the issue when a window is created under a mouse cursor or 
>>> it is moved under a mouse cursor the system does not generate the 
>>> NSMouseEntered event.
>>> It is possible to synthetically generate the MouseEntered event for  
>>> window creation and moving in Java because we need that a window 
>>> behavior on Mac OS X was the same as on others platforms.
>>> But it is necessary to have a way to know is this window the topmost 
>>> under a mouse cursor.
>>> Thanks,
>>> Alexandr.

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