|static NamedStyle *||default_style = &::style|
This subclass pops up a menu in response to a user click. The menu is popped up positioned so that the mouse is pointing at the last-selected item, even if it in a nested submenu (To turn off this behaivor do value(-1) after each item is selected)
Normally any mouse button will pop up a menu and it is lined up above the button, or below it when there is no previous selected value as shown in the picture.
However a PopupMenu can also have type() set to POPUP1, POPUP2, POPUP12, POPUP3, POPUP13, POPUP23, or POPUP123. It then becomes invisible and ignores all mouse buttons other than the ones named in the popup type. You can then resize it to cover another widget (or many widgets) so that pressing that button pops up the menu.
The menu will also pop up in response to shortcuts indicated by the shortcut() or by putting '&x' in the label().
Typing the fltk::Widget::shortcut() of any menu items will cause it to be picked. The callback will be done but there will be no visible effect to the widget.
This style is assigned to Menu subclasses.
Because of the need to be compatable with Windows, which has a somewhat inconsistent appearance, the default is different than Widget::default_style, and the usage of the fields is somewhat unusual:
The Browser subclass sets the style back to Widget::default_style, so that they appear more like a text editor (ie they put the color and leading back to normal).
Reimplemented from fltk::Menu.