I have a very simple code, which create a GtkWindow and places in it a GtkButton.
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_widget_set_size_request(_window, 800, 450);
gtk_window_set_decorated(GTK_WINDOW (_window), FALSE);
gtk_window_set_position(GTK_WINDOW (_window),GTK_WIN_POS_CENTER_ALWAYS);
gtk_window_set_resizable(GTK_WINDOW (_window), FALSE);
_startbutton = gtk_button_new_with_label("myLabel");
gtk_container_add(GTK_CONTAINER(_window), _startbutton);
gtk_widget_show_all(_window);
Yet, this doesn't work as expected because the button fills the whole window. I tried to find a way to change the button size, but all the methods that I found use some methods that are deprecated... Can someone explain to me the way to do this?
Because the GtkButton is the only control in the GtkWindow, it will be given the entire area of the GtkWindow to fill. If you want to do anything more complicated, you will need to use layout containers like GtkBox and GtkGrid to explicitly lay out the button, usually in relation to other controls that you will also have in the window.
Once you do lay out your controls, you can use expansion and alignment to control how the button makes use of its allotted space.