Tool settings stroke width

I've implemented the functionality that is described here: https://github.com/Catrobat/Paintroid/issues/84
If the screen is small (see my comment at the above link):
minWidth and minHeight for mdpi is 80dp so when user set the width to 81+ the circle or rectangle doesn't change (because if we set the ImageButtons sizes to real stroke width the whole layout width will be bigger than dialog width).
This dialog is correctly displayed in all screens.