FVWM: avoiding crosshair when thumbnailing

For the moment I don't have access to my old config files, so I have
to solve this once again. Hope for some help from the community.

To get thumbnails within fvwmpager, I do as following.
#-----
DestroyFunc GoLeft
AddToFunc GoLeft
+ I Mini_Thumbnail
+ I ShowPager
+ I PipeRead '\
	if [ $[page.nx] -gt 0 ]; then\
		echo GotoPage -1p 0p;\
.....
### Put all SetEnv in infostore
SetEnv fvwm_mini_icon_size   63

DestroyFunc Mini_Thumbnail
AddToFunc Mini_Thumbnail
+ I Raise
+ I SetEnv MiniIcon-$[w.id] $[w.MiniIconFile]
+ I ThisWindow (!Shaded,  !FvwmPager, !Iconic) PipeRead \
    "$[FVWM_USERDIR]/bin/thumb $[w.id] $[fvwm_mini_icon_size]
$[FVWM_USERDIR]/tmp/mini_icon.tmp.$[w.id].png $[w..MiniIconFile]\
		&& echo WindowStyle EWMHMiniIconOverride, MiniIcon
$[FVWM_USERDIR]/tmp/mini_icon.tmp.$[w.id].png || echo Nop"
#-----

But the call to ThisWindow gives me a crosshair in thoose cases where
there is no window below the mousepointer.
How do I avoid the crosshair.?

/Peter Holm