I believe that i just found a temporary workaround. Since the flickering seems to be caused by the automatic mode detection on my non-connected VGA output, I used xrandr to force a mode on that output.
I used the following commands xrandr --newmode dummy 75.00 1280 1301 1333 1408 800 804 808 816 -hsync -vsync xrandr --addmode VGA dummy xrandr --output VGA --mode dummy Those commands cause a lot of flickering but after them, flickering is gone. The result can be verified with $ xrandr --prop | cat -n 1 Screen 0: minimum 320 x 200, current 1280 x 800, maximum 1280 x 1280 2 VGA disconnected 1280x800+0+0 (normal left inverted right x axis y axis) 0mm x 0mm 3 dummy 65.3* 4 LVDS connected 1280x800+0+0 (normal left inverted right x axis y axis) 261mm x 163mm 5 EDID_DATA: 6 00ffffffffffff0006af142100000000 7 010f0103801a10780a30259855548827 8 24505400000001010101010101010101 9 0101010101014c1d0080502010301520 10 440005a3100000190000000000000000 11 00000000000000000001000000fe0057 12 35333832004231323145570a000000fe 13 00fffdf3e9bb8d6f0001010a2020005f 14 PANEL_FITTING: full 15 supported: center full_aspect full 16 BACKLIGHT_CONTROL: native 17 supported: native legacy combination kernel 18 BACKLIGHT: 0 (0x00000000) range: (0,0) 19 1280x800 65.3*+ 20 1024x768 60.0 21 800x600 60.3 22 640x480 59.9 23 TV disconnected (normal left inverted right x axis y axis) 24 BOTTOM: 37 (0x00000025) range: (0,100) 25 RIGHT: 46 (0x0000002e) range: (0,100) 26 TOP: 36 (0x00000024) range: (0,100) 27 LEFT: 54 (0x00000036) range: (0,100) 28 TV_FORMAT: NTSC-M 29 supported: NTSC-M NTSC-443 NTSC-J PAL-M 30 PAL-N PAL The interesting line is 3 which indicates that my "dummy" mode is activated for the VGA output. PS: I used a 1280x800 mode because this is the resolution of my laptop panel and, somehow, using a smaller resolution caused my gnome panels to be resized. -- Flickering with version 2.4.0 https://bugs.launchpad.net/bugs/256142 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs