Unfortunately, I have no idea what .swf files are. (My best guess is that it stands for 'Shockwave Flash'.)
That's right. I dabbled a bit with these files to remove the questmarkers and was successful. Motivated by that achievment I tried to edit the bottomBar files (the _c files are for controllers) to extend the bottom bars (additional slots for each bar). To put it in a nutshell (if to hand): I changed the bars visually and was even able to make the new slots get recognized when the mouse pointer drags items/skills over the slot. But the result was: the items disappeared in the black hole of the new slots and reappeared somewhere else (to be precise: an item that fell into slot 13 on bar 1 appeared in slot 3 of bar 2, magic hat). And beyond 50 the game crashed.
So, if you have programming knowledge it shouldn't be too difficult to do that. Otherwise you will end up like me.
EDIT: Maybe it would be easier to just add new bars but I haven't found out where the number of bars is defined. Not quite helpful, sorry!