How to force an application window to be automatically maximized after starting the application?

Question

I tried to use Docky, then I removed it and after that my browser (Chromium) can't be opened in maximum height, every time I should maximize it myself. (XFCE desktop)

Answer 1

How to startup an application (any) maximized

Starting an application via the script below, you can force any application* to startup maximized. If you either replace the main command in (a copy of-) your .desktop file by the command to run the script (see further below how to do that) or add it as a quicklist shortcut, you can achieve exactly what you want.

(* Some applications have a fixed, unchangeable windowsize, some windows open a new tab in a possibly already opened window)

About the script

The script runs with the command:

python3 /path/to/script <application>

The script:

• first runs the command to open the application
• to prevent timing issues, it then waits for the application's (new) window to appear (by finding a match between its pid and the id of the corresponding window) in the output of the wmctrl -lp -command (for only 15 seconds, to prevent an infinite loop)

• Once the window appears, it maximizes the window with the command:

  xdotool windowsize <window_id> 100% 100%
  

The code

#!/usr/bin/env python3
import subprocess
import getpass
import time
import sys

app = sys.argv[1]

user = getpass.getuser()
get = lambda x: subprocess.check_output(x).decode("utf-8")
ws1 = get(["wmctrl", "-lp"]); t = 0
subprocess.Popen(app)
while t < 30:      
    ws2 = [(w.split()[2], w.split()[0]) for w in get(["wmctrl", "-lp"]).splitlines() if not w in ws1]
    procs = sum([[(w[1], p) for p in get(["ps", "-u", user]).splitlines() \
              if app[:15].lower() in p.lower() and w[0] in p] for w in ws2], [])
    if len(procs) > 0:
        subprocess.call(["xdotool", "windowsize", "-sync", procs[0][0] , "100%", "100%"])
        break
    time.sleep(0.5)
    t = t+1

How to use

1. The script needs both wmctrl and xdotool

   sudo apt-get install wmctrl xdotool
   

2. Copy the script above into an empty file, save it as run_maximized.py

3. Now edit your .desktop file:

   • Copy the global .desktop file locally:

     cp /usr/share/applications/chromium-browser.desktop ~/.local/share/applications
     

XFCE version:

4. open the file with gedit:

   gedit ~/.local/share/applications/chromium-browser.desktop
   

   Browse to the line:

   Exec=chromium-browser %U
   

   (which is the first line, starting with Exec=

   Change it into:

   Exec=python3 /path/to/script.py chromium-browser
   

   where you need to replace /path/to/script.py by the actual path.

5. Log out and back in. From now on, your Chromium launcher will open Chromium maximized.

Unity version:

4. open the file with gedit:

   gedit ~/.local/share/applications/chromium-browser.desktop
   

   Browse to the line:

   Actions=NewWindow;Incognito;TempProfile;
   

   Change it into:

   Actions=NewWindow;Incognito;TempProfile;divider1;Open maximized;
   

   The add to the very bottom of the file the section below:

   [Desktop Action Open maximized]
   Name=Open maximized
   Exec=python3 /path/to/script.py chromium-browser
   OnlyShowIn=Unity;
   
   [Desktop Action divider1]
   Name=.....................................
   OnlyShowIn=Unity;
   

   where you need to replace /path/to/script.py by the actual path.

5. Log out and back in. From now on, your Chromium launcher looks like:

   

Important note

In a .desktop file, you must use absolute paths; ~ won't work for example. This counts for .desktop files in /usr/share/applications, ~/.local/share/applications as well as commands in Startup Applications (which are actually called by .desktop files in ~/.config/autostart).