Fl::Window - Window Container for Widgets


    use Fl;
    my $window = Fl::Window->new(350, 500, 'Hello, World!');


This widget produces an actual window.

This can either be a main window, with a border and title and all the window management controls, or a "subwindow" inside a window. This is controlled by whether or not the window has a parent().

Once you create a window, you usually add children Fl::Widgets to it by using <$window-add($child)>> for each new widget. See Fl::Group for more information on how to add and remove children.

There are several subclasses of Fl::Window that provide double-buffering, overlay, menu, and OpenGL support.

The window's callback is done if the user tries to close a window using the window manager and Fl::modal() is zero or equal to the window. Fl::Window has a default callback that calls <Fl::Window-hide()>>.


In addition to inheriting from Fl::Group, this widget also supports the following methods.


The constructor creates a window of a given size and (optionally) position on screen. The upstream API has a few poorly designed options:

    my $window_a = Fl::Window->new(300, 500);

This creates a window from the given size. You may also set the window's title like this:

    my $window_b = Fl::Window->new(300, 500, 'Basic math');

If not provided, the window's title defaults to the filename of the current running script.

You'll notice that the above examples don't define an on screen position. The window manager is allowed to place the new window as it sees fit. To define a position yourself, use either:

    my $window_c = Fl::Window->new(100, 150, 300, 500);


    my $window_d = Fl::Window->new(100, 150, 300, 500, 'Math is singular');

In these examples, the new window is placed 100 pixels from the left and 150 pixels down from the top of the display area.

Again, the ($w, $h) form of the constructor creates a top-level window and asks the window manager to position the window. The ($x, $y, $w, $h) form of the constructor either creates a subwindow or a top-level window at the specified location ($x, $y), subject to window manager configuration. If you do not specify the position of the window, the window manager will pick a place to show the window or allow the user to pick a location. Use position($x, $y) or hotspot() before calling show() to request a position on the screen. See Fl::Window-resize()/resize(...)> for more details on positioning windows.

Top-level windows initially have visible() set to 0 and <parent()> set to undef. Subwindows initially have visible() set to 1 and parent() set to the parent window pointer.

Fl::Widget->box() defaults to FL_FLAT_BOX. If you plan to completely fill the window with children widgets you should change this to FL_NO_BOX. If you turn the window border off you may want to change this to FL_UP_BOX.

The destructor also deletes all children. This allows a whole tree to be deleted at once, without having to keep a pointer to all children in the user code.


Puts the window on the screen.

On X, this usually has the side effect of opening the display.

If the window is already shown, it is restored and raised to the top. This is really convenient because your program can call show() at any time, even if the window is already up. It also means that show() serves the purpose of raise() in other toolkits.


Returns non-zero if show() has been called but not hide().

You can tell if a window is iconified with ( $w-shown() && !$w->visible() )>.


Removes the window from the screen.

If the window is already hidden or has not been hsown then this does nothing and is harmless.


Copyright (C) Sanko Robinson.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


Sanko Robinson <>