[lazarus] Mouse fixes

[Mattias Gaertner]

Hi all,

I have fixed the mouse coordinates and the mouse-click-on-parent bug.

The mouse coordinates of OnMouseDown/Up/Move are now relative to the client area of the control.

The mouse-click-on-parent bug was for example: 
Clicking on the tabs of the component notebook in the IDE resulted also in a click on one of the toolbuttons to the left (New, Open, Save, ...). If u don't know, what I mean, don't worry, it's gone. :)


Will now check the grabbing ...

Mattias