taskbar TaskItemButton content margin

[goutofashion]

hi, i'm working on a theme/visual style and i ran into some trouble getting the margins right for the taskitembuttons.

i want to have square taskitem buttons and it works if i use 10,10,10,10 or 20,20,20,20 as content margins with big icons and small icons (9,9,9,9 is the lowest that works i guess).
but the problem with that is: if i set a margin that high the taskbar gets higher then i want it.
if i'll try to set lower margin settings something very strange appears in the visual style: the left and right margins are going completly wrong.

here is what it looks like:

Taskbar & System Tray > TaskBand > Basic > TaskBand > TaskItemButton > CONTENTMARGINS:MARGIN > 10, 10, 10, 10
65726
Taskbar & System Tray > TaskBand > Basic > TaskBand (SmallIcons) > TaskItemButton > CONTENTMARGINS:MARGIN > 10, 10, 10, 10
65725

... both working as expected but as i said its too high for my taste.

but when i'll try to set a lower margin-setting this appears:

Taskbar & System Tray > TaskBand > Basic > TaskBand > TaskItemButton > CONTENTMARGINS:MARGIN > 5, 5, 5, 5
65723
Taskbar & System Tray > TaskBand > Basic > TaskBand (SmallIcons) > TaskItemButton > CONTENTMARGINS:MARGIN > 5, 5, 5, 5
65724

anybody has an idea what is going wrong there ?
why the lower margin settings get so wide ?

any solution ?

thx for help