switchable between Tk (standard Tcl/Tk widget set) and
Ttk (Tile). Initial default widget set is Tk. Now, toplevel
widget classes are removed and defined as aliases.
For example, "TkButton" is an alias of the "Tk::Button" class.
Those aliases are replaced when switching default widget set.
"Tk.default_widget_set=" is the method for switching default
widget set. "Tk.default_widget_set = :Ttk" defines Ttk (Tile)
widget set as default. It means that "TkButton" denotes
"Tk::Tile::Button" class. And then, "TkButton.new" creates
a Tk::Tile::Button widget. Of course, you can back to use
standard Tk widgets as the default widget set by calling
"Tk.default_widget_set = :Tk", whenever you want. Based on
thie feature, you can use Ttk widget styling engine on your
old Ruby/Tk application without modifying its source, if you
don'tuse widget options unsupported on Ttk widgets (At first,
call "Tk.default_widget_set = :Ttk", and next load and run
your application).
This is one step for supporting Tcl/Tk8.5 features.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@15618 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
