Add accelerators for control panel open and close

[quozl]

There is no accelerator for opening or closing control panel. This hinders use, requiring mouse or touchscreen. See #4660.

View Source has Alt+Shift+V for open, and Escape for close. Activities have Ctrl+q for close. Wireless Key Required dialog has Escape for close.

Patch adds accelerators:

1. Alt+Shift+M to open control panel, valid in any Sugar screen or activity, and;
2. Escape, Ctrl+q or Ctrl+Shift+q to close control panel or sections.

Close accelerator is added in the key event callback, rather than using ToolButton accelerators, because they do not work in the control panel.

Test case: use Alt+Shift+M to open control panel, verify q alone, and Shift+Q do insert into search box, select a section, verify Ctrl+q, Ctrl+Shift+Q and Escape closes section, and closes control panel.

References:

• HotKeys page on Wiki,
• Ticket #4660 (keyboard navigation of Sugar), and;
• Pull Request #443 (keyboard navigation of control panel).

[samdroid-apps]

Reviewed.

1. This patch allows you to open many copies of the control panel. Pressing Alt-Shift-M should not open another panel if there is currently one open. Other shortcuts (view source tested) already deal for this edge case
2. Esc is good and conststant, however other dialog (view source tested) do not use Ctrl-Q. Maybe only add Esc?

This is a very good patch otherwise!

Also, another easy target for the control panel: make enter do something on the grid view!

[godiard]

Just a comment: In src/jarabe/model/shell.py, we have a array self._shell_windows,
and two methods push_shell_window() and pop_shell_window() to track the windows opened,
and close them when needed.
Probably we should add a function has_shell_window() then we can control if a window is opened before opening one more.

[samdroid-apps]

Or maybe only have 1 global instance of the control panel? Then you can only show and hide the window - and that is all you need!