Improve layout of showActivityManager applet
Fixes an issue where the showActivityManager applet was too small and caused some applets on the panel to overlap.
Also fixes two issues I found while testing the change:
- There was an extra small spacing on the right of the applet when not displaying the activity name.
- The activity name could go past the widget when placed on the desktop.
One problem that I couldn't solve is that when you place a new showActivityManager widget on the desktop the initial width isn't big enough to contain the icon and text.