I try to use HEADERBAR, but cannot found information about how add it to non-toplevel-window/widget. I need to allow user to move window, but only in certain condition (when user invokes specific window mode). I see Firefox work with PIP (Picture-In-Pictrue mode) with that. How?
I use this code:
GtkHeaderBar *HB = gtk_header_bar_new();
GtkBox *box = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 0);
gtk_box_pack_start(box, HB, 0, 0, 0);
gtk_overlay_add_overlay(p, box);
gtk_widget_show_all(box);
It do not work. I see Box layout (I see background on top of other widget), but no headerbar.