use ThumbnailHolder with preview. it works, but thumbnail headers don't work, so they are not shown in this mode.
convert extension to an applet
fix null-access error triggered when closing windows from Alt-Tab
don't let gradients overlay the item list when not active, as it hurts the item-hover detection
more conservative defaults
fix mouse-hover-over-invisible-arrow problem
one setting was missing the BIDIRECTIONAL property
guard against spurious motion events

strangely enough, minimizing a window will lead to one of these occurrences
update README