Some of you will hate me for this :) I've just released yet another Slax version. This one should fix the plasma task bar finally. If not, then I'll give up :) Anyway, if you do not like to download new Slax each two days, feel free to use 7.0.6 or 7.0.7 and just resize the taskbar manually to full screen width if you need.
What is the problem with the plasma bar anyway? The root of the issue is in the way how the settings are stored for it. If a height is to be specified, which I need for slax, then a width must be specified as well. If a width is specified which is smaller than user's desktop size, it sometimes adapts the task bar to full width, but sometimes it doesn't. However I found out that if really big width is set, which is bigger than the screen, it adapts to actual screen width properly. So I set there 8000 pixels, in the hope that all Slax users will have smaller screen :)