fvwm-buttons, colorsets and pixmaps

I want to have a transparent button which display only a png, and when the cursor is mover over the button, or the button is clicked, I want the png to change. I can get it to work, but without transparency on the pixmaps.

So, I try another way, to iconify the button and change it icon picture with FvwmAuto and the Style. It work fine, but give me a lot of flickring at the screen. The flickering is so bad it can even hang mplayer…

EDIT: I was wrong on this. The flickering is due to something else. EndEdit

So I am back to the first case. I try every thing, I can get a transparent button, but as soon I put the pixmaps, the transparent parts of the pixmap never show the root background.
I try with and without background colors, with and withour Alpha and Tint, nothing helped.

[code]# active items
Colorset 13
RootTransparent, Transparent, fg #000000, bg #e5e5e5,
Pixmap 48x48/categories/Boing_4.png.active.png

inactive items

Colorset 14
RootTransparent, Transparent, fg #000000, bg #e5e5e5,
Pixmap 48x48/categories/Boing_4.png

DestroyModuleConfig FvwmButtons-Drive1: *
KillModule FvwmButtons FvwmButtons-Drive1
*FvwmButtons-Drive1: Pixmap none
*FvwmButtons-Drive1: Font “xft:$[panel_font]”
*FvwmButtons-Drive1: (1x1+0+0)
*FvwmButtons-Drive1: Colorset 14
*FvwmButtons-Drive1: ActiveColorset 13
*FvwmButtons-Drive1: PressColorset 13
*FvwmButtons-Drive1: Geometry 48x48+30+30
Module FvwmButtons FvwmButtons-Drive1

Style FvwmButtons-Drive1 ParentalRelativity

Is it possible to archive normal transparency to the root background with a pixmap in a button colorset, and if yes how?