If I click on a software icon on Ubuntu, or a menu entry, and then before the program opens I quickly change to a different workspace, the program opens not in the workspace in which I clicked the icon but in the current one. This is very annoying to me. How can I try and fix that?
I think it is just part of how the desktop works... A single desktop can be divided up into multiple workspaces, but those workspaces are not as autonimous as they may seem. eg. they don't hold their own mouse position. You mouse stays in the same position as you move between the workspaces of a desktop.. And the same appears to be the case with launching apps.. An app is launched "by the desktop" and if by the time it materializes (creates its window) you have moved the terrain (workspace), then it presents itself there; in the new workspace.
devilspie is available in the Ubuntu repository, and there is a GUI front-end for it, called gDevilspie, availabel at code.google.com/p/gdevilspie
Another very useful tool (command-line) for such desktop/workspace/app manipulation is called
devilspie is probably your best simplest option, because, as I've personally found out, working around this existing built-in behaviour may give a technically working result, but it can be simpler (practically speaking) to just adapt to how the desktop works as-is.