Adds a new highlighting effect to the actively selected row in
ComboBox ListView. ComboBoxEditor can now be controlled with
page up, page down, and the up and down arrow keys. ESC and loss
of focus now cause comboboxes to close. Now activates on mouseup
as well as return.
Adds a new, more restrictive read-only state to TextEditor which
forbids copying, selecting, editor cursors, and context menus.
Provides a unique appearance on focus which accomodates ComboBox
widgets. All TextEditor modes are now accessed by enum and
set_mode() which sets the editor to Editable, ReadOnly or
DisplayOnly. Updates applications still using set_readonly().
This is much better than the hack we had of making them Tooltip windows
since frameless windows end up at the right layer in the window stack
automatically, and always get yanked above the parent window simply by
being child windows.
