Its the negative left content margin for the all progs background that shifts the text over 1 image state.(approx half the width negative of the backgrounds width)Do not touch the right content margin.
The arrow graphic must be exactly the same width as the background and be opaque(or the mouseover color will show thru in translucent areas)
Upper and lower content margins determine how tall your arrow graphic must be.
There can be NO semi-transparent pixels in either image parts that are within the content margins.You can have both opaque and totally blank areas at the same time.(like some empty space to the left of the menu,for SM's that dont sit on the screen edge)
Watch for stray pixels like shadows that might have extended left past the true edge of the menu.
Text angle of 900 just aligns the text vertically so different languages do not move the arrow around.(the arrow graphic covers what little would show if you didnt use an oversized arrow)
Test with large and small icons on the progs side because you may need to tweak the negative amount to work for both...final test with a different language...sometimes you just have to play with it to hit the sweet spot.
Slider is done this way and so far not one complaint ... cross fingers.
This was done in SKS5...I cant vouch for SKS6 or Vista.