Stacking widgets in Gtk+

Question

Is there a way in Gtk+ to stack one widget on top of another -- not counting GtkFixed? GtkFixed doesn't work well for two reasons: 1) I need Z order, and 2) I need one widget to stretch and fill provided space.

Answer 1

I don't think there is a proper container in standard GTK. I would subclass Gtk::Fixed... it is still the closest one you can get, and if you use gtkmm then subclassing shouldn't be very difficult¹. Then you can control the dimensions of all widgets, stretching one selected child to fill space.

To control Z-axis you will probably need to manipulate widget's X windows--check GDK documentation on topic of GDK windows². I remember that in PyGTK each widget has gtk.Widget.window property, I guess that the same is for gtkmm. This assumes that all your child widgets have X windows, so f.e. you'll need to wrap Gtk::Label inside Gtk::EventBox.

¹ http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/chapter-customwidgets.html

² http://www.gtkmm.org/docs/gtkmm-2.4/docs/reference/html/classGdk_1_1Window.html#6eef65b862344ad01b01e527f2c39741

Answer 2

I had this exact issue using a Gtk::Fixed (actually gtk.Fixed -- pygtk -- but I think it's all the same underneath) and I was able to handle it quite easily by manipulating each widget's window.

In my case, the widgets already are EventBox instances, and I just needed to make sure that the one I was dragging around was on top, because otherwise it slid underneath others, which looked quite wrong. The solution was as simple as calling "widget.window.raise_()" to raise the widget's underlying window when the widget was clicked to begin the drag.

So I'm basically just reaffirming that the previous answer works, but I wanted to point out that it's actually pretty easy. It sounds like you may need to create some EventBoxes to hold your widgets, but after that it should just work.

You can see the code I was working on at http://github.com/divegeek/BlockHead

Answer 3

I was able to do exactly that -

display one widget filling the entire space, and then another on top at a fixed location, both visible at the same time

in gtk2 by using GtkFixed, working out a suitable insertion order (first inserted - bottom, last inserted - top), and - most importantly!! - forcing GtkFixed to have it's own window:

`f := gtk_fixed_new();
gtk_widget_set_has_window(f, 1);`

If you don't do set_has_window(f, 1), all children windows will be inserted into some parent widget/window (see gtk_fixed_realize() in gtkfixed.c), and that might create z-order mess.