When I minimize an app in Ubuntu 11.04 using Unity, where does it go? I can ALT+TAB them but that is about it. Where do I visually see them or at least a small icon that tells me where they are and how many windows of that type are opened (Like 4 windows of Firefox I have).
They should be in the launcher, which you can reveal by moving your mouse to the top-left corner or by pressing and holding the Super (Windows) key:
Note, that you can scroll down by moving the cursor to the bottom edge or use the mouse wheel.
If you don't like that behavior, you can install the CompizConfig Settings Manager (package compizconfig-settings-manager) and change the hide mode of the launcher (see this question: How can I configure Unity's launcher auto-hide behavior?).
The focused application will show an arrow on the right side of its icon, while the left side arrows show how many windows are opened: one arrow for one window, two arrows for two windows, and three arrows for more than two windows.
