Painting on Scrolling Buttons

Its not really important to get the Buttons with images on to work, but its a good opportunity to test my way of drawing to standard MUI Classes. The drawing was not a real problem but to calculate the position and sizes is really trouble and much work. I’m still not sure if it is working right for every case (size of Glyph, Length of Text, Height of Text, Position of Glyph). But as first implementation it is ok so.
The other thing , a little bit more important, I implemented Scrollbars, rather easy, just the property names are a little bit strange and the LCL Event was not so obvious.

BitBtn and Scrollbars AROS (top) and Linux (bottom)