Re: Wrong Canvas.MouseUp Event?

[Jim Dossey <jim.dossey@gmail.com>]

On Thu, Apr 30, 2009 at 5:34 AM, Tom <tom@helios.de> wrote:

> Hi List!
>
> The Language reference states:
>
>> Canvas.MouseUp Event:
>> The mouse button was released inside the Canvas region at the location
>> passed in to x,y.
>>
>
> But the event also occurs when the mouse is released _ouside_ of the
> canvas!
>
> To reproduce this:
> make a new project and put a canvas and an Editfield on the Window. Make
> the EditField multiline.
> In the Canvas events add following code
>
>>        Sub Paint(g As Graphics)
>>          g.ForeColor = &cFFAB60
>>          g.FillRect 0,0,me.Width, me.Height
>>        End Sub
>>
>>        Function MouseDown(X As Integer, Y As Integer) As Boolean
>>          EditField1.AppendText "MouseDown, x=" + str(x) + ", y=" + str(y)+
>> EndOfLine
>>          return true
>>        End Function
>>
>>        Sub MouseUp(X As Integer, Y As Integer)
>>          EditField1.AppendText "MouseUp, x=" + str(x) + ", y=" + str(y)+
>> EndOfLine                  End Sub
>>
>
> Now click the canvas and drag the mouse outside of it. Then release the
> mouse key.
> I think there should be no MouseUp Event because the mouse is not released
> _inside_ of the Canvas area.
> Tested on Mac and Win XP.
>
> This looks like a bug for me. Comments please.


I don't see this as a bug.  For example, a user might click on a control and
then realize that was a mistake.  So they move the mouse out of the control
before releasing the button.  By checking the X,Y coordinates you can see
what the user did and take the appropriate action.  There are probably other
much better reasons for having mouseup events outside of the control.
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