This is just a minor bug, but it gets worse the slower your computer is and the darker your wallpaper is. To reproduce and to see it as much as possible: 1. Select a dark wallpaper (preferably all black; it doesn't matter if you use an image as backdrop) 2. Select a wm theme that doesn't have any borders at the right and left side of the windows, like Metabox. 3. Open up a single terminal, like xterm or Terminal. 4. Resize it to cover roughly 75% of the width and height of the screen. 5. Move it from the right to the left (moving it up and down won't make it as visible). The areas that have been previously covered by the window will be white, until they've been redrawn. (Note that steps 1-4 and parts of step 5 are just there to make it as visible as possible; if you still can't see it you may want to switch to a slower X driver, like vesa. Also, note that it wasn't visible anymore when I turned on composite.) This is actually a major annoyance on an older laptop I've got, a p2 300 with 64 mb ram, which xfce runs on very well in all other aspects. 4.4b1 actually uses less memory on it than 4.2.3.2 did :) This problem is also visible on my new laptop (pm 1.86ghz, 1gb ram, running xfce svn), but far from as visible as on the older one. If I'm not wrong (I may very well be), this problem was introduced into xfdesktop when desktop icons were implemented. At least I never saw it before that period.
Yeah, drawing is handled differently now. Instead of passing a pixmap to the server to draw the background for us, xfdesktop takes care of repainting the background when it's exposed. I was looking at this last night; I was trying to set the back pixmap on the server to the background image, and then just have xfdesktop draw the icons on top of that, but it didn't fix the problem, and I'm not sure why. I'll look into it a bit later; this is certainly annoying and ugly.
Ok, this should be much improved. The icons themselves probably show the same tearing as before, but the backdrop image should redraw smoothly as before.