Install a Recommended Package When User Requests Action

You don't upload a .deb package, you upload a source package, which can be built in to a .deb package.

This is then put in a PPA to build the .deb packages that users will install.

Therefore there is a PPA behind the scenes.

You can then submit updates to your application by uploading an updated source package at a later date. This will then be reviewed and go through QA before being made available to users.

I look forward to seeing your application in the Software Center.

Assuming that you are talking about an ordinary button (as supposed to a togglebutton) you can see all the methods it has here. As I read it there does not seem to be a function for what you are looking for, probably because these things are designed to be event driven.

In any case, I am wondering, can't you just get the events to set a boolean and have a look at that to see if it is pressed. Otherwise, maybe you can explain the rationale of why it is important to you to go around the events.

EDIT

After realizing that I misread you original post and that you were talking about keyboard keys and not buttons I came up with the following suggestion.

When the program is run, it will make a gtk window and hide it, to make it possible to listen for keyboard events. Then it will listen for key released events from any of the keys that are in the shortcut that started the program (in this case ctrl-alt-u). If any of those keys are released, within the start up timeout, it will quit at the end of the timeout, otherwise, it will show the program.

If you want to delay the actual start of your program code to save resources, you can of course just use a dummy window and not load the real window or any of the underlying classes before in the start_or_not function.

import pygtk
pygtk.require('2.0')
import gtk

class DelayedStart:

    def __init__(self):
        self.w = gtk.Window()
        self.w.connect('destroy', gtk.main_quit)
        # Connect key released events to a function
        self.w.connect('key_release_event', self.on_key_press_event)
        self.w.show_all()
        # Hide the window, we actually need a gtk window to listen for
        # keyboard events, so we just hide it
        self.w.set_decorated(False)
        self.w.set_opacity(0)

        self.show_on_timeout = True
        # Ask gtk to call the this function in 2 seconds
        gtk.timeout_add(1000*2, self.start_or_not)
        gtk.main()

    def on_key_press_event(self, widget, event):
        """ Check if any of the key in the shortcut ctrl-alt-u is released """
        # ctrl = 65507, alt = 65513, u = 117
        keys = [65507, 65513, 117]
        if event.keyval in keys:
            self.show_on_timeout = False

    def start_or_not(self):
        """ Check if the program should be started or not """
        if self.show_on_timeout:
            self.w.set_decorated(True)
            self.w.set_opacity(1)
        else:
            gtk.main_quit()
        # Returning false will destroy the timer, we only want to run this once
        return False

if __name__ == "__main__":
    DELAYED_START = DelayedStart()