add support for touchscreens

[erwindon]

Is your feature request related to a problem? Please describe. Some elements of the GUI depend on the mouse-enter/mouse-leave/mouse-over events. However, these do not occur for touchscreens (i.e. tablets, phones, etc.)

Describe the solution you'd like Have a GUI that is also compatible with touch screens

Additional context e.g.:

1. menu panels from the main menu bar do not hide after a selection
2. same for popup menus
3. the task summary (for highstate jobs) cannot be made visible in job result
4. the task summary (for highstate jobs) cannot be made visible in highstate page
5. ctrl-click to see Options/Stats is not possible

[erwindon]

1. menu panels are now hidden after use, but touchscreen still think the mouse is over them and keep them visible
2. see previous
3. never mind, too much trouble
4. see previous
5. Added DBLCLICK handler --> OK