How can I open a window on a different monitor?

With multiple monitors, I have so far been dragging windows manually around. Is there a way to make a window open on a specific screen in a dual-head setup? (Not to be confused with multiple X server displays.) Something like: SCREEN=2 firefox or open-in-screen 2 firefox. If it matters, my environment is KDE using the KWin window manager. KWin window rules can only match some properties like title, but I could not find an environment variable as filter. The secondary display extends the primary screen: $ xrandr -q Screen 0: minimum 320 x 200, current 3520 x 1080, maximum 32767 x 32767 LVDS1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 382mm x 214mm 1600x900 60.1*+ 1024x768 60.0 800x600 60.3 56.2 640x480 59.9 VGA1 disconnected (normal left inverted right x axis y axis) HDMI1 connected 1920x1080+1600+0 (normal left inverted right x axis y axis) 477mm x 268mm 1920x1080 60.0* 50.0 59.9 1920x1080i 60.1 50.0 60.0 1680x1050 59.9 1280x1024 75.0 60.0 1440x900 59.9 1280x960 60.0 1280x720 60.0 50.0 59.9 1024x768 75.1 70.1 60.0 832x624 74.6 800x600 72.2 75.0 60.3 56.2 720x576 50.0 720x480 60.0 59.9 640x480 75.0 72.8 66.7 60.0 59.9 720x400 70.1 DP1 disconnected (normal left inverted right x axis y axis)