Only single click used for element selection does not work.Recently I tried the Wacom tablet to be sure it works well at other CAD software.I confirm the same behaviour with my Wacom Intuos3 9x12 tablet using a STYLUS pen.
I used friends PC with Windows 7 Autocad Solid Edge and there wasn't any problem with it. Not in Free CAD per se but in one of its third-party libraries.
You said you have the same problem with Krusader which is a KDE-based package. I suggest you try to use it in another app that relies on Qt for its GUI.
Libre In Kursader I have that problem at one concrete situation (sort of file listing) otherwise the Wacom pen (its left mouse button click) and Krusader works together quite well.
Do you have any other suggestions or software I would have to test?
I'll try to narrow it down, but if you have any tips, please le me know. Hovering is like moving mouse, touching the surface with the tip of the pen is like the left click and there is a rocker button oon the pen that works as right/middle click.
I can't find the place in the code where unselecting after "empty" left click takes place.
Finally if for moving and selection I use only the Wacom pen the moving works but selection doesn't.
But it is strange that I can use drag&drop feature with Wacom pen.
If I use touchpad or trackpoint of my notebook (first move mouse cursor over an element and then click without any other cursor moving) selection works well.