> > I switched to Blackbox from KDE. I really liked the fact that you could > set a different background image for each desktop, but I also remember > that, as you suggest here, it was really, really slow -- every time you > switched desktops there was a short but noticeable pause where it would > switch background images. > > So considered from this perspective, I guess it is not so desirable a > feature. :) >
Some window managers (like E) create a large window the size of the screen and pretend it is the root window. They create one of these per workspace/desktop/whatever. This is how E has a new image for every workspace -- each workspace is actually a new thing. kwin may do something similar via the desktop window which shows the icons or it may simply reset the background every time the current workspace is changed. What mackstann said is correct and accurate. I would only add a description of how workspaces work under blackbox (and most other wms). When you chose to change workspaces blackbox first sanity checks to make sure the new workspace actually exists. Then it takes every window on the current workspace and withdraws it (this is similar to iconifying them, but they do not appear as icons). It then updates the menus and toolbar to reflect the new workspace. Finally it redraws all of the windows which were withdrawn from the new workspace and marks the workspace current. What E does is map and unmap the desktop window. Think of this as having several pages in a picture book and it just manipulates which picture is on top. This also breaks most every X app that ever wanted to touch the root window -- xsnow, fishtank, screen savers, background programs, etc. The root is now permanently hidden.
