Window Border Corruption (Dashed and/or Dotted Lines Frequently Appearing on Bottom Border of Windows)

[bongochong]

Under Xubuntu 14.04 using Compton instead of Xfce's compositor, I often notice some artifacts on the bottom border of windows. This most frequently occurs with Xfce Terminal and Firefox, though I've seen it show up under myriad other applications.

Here are some screenshots of the problem occurring in Firefox:

Here is my Compton config file:
backend = "glx";
glx-no-stencil = true;
glx-copy-from-front = false;
glx-swap-method = "3";
shadow = true;
no-dnd-shadow = true;
no-dock-shadow = true;
clear-shadow = true;
shadow-radius = 6;
shadow-offset-x = -7;
shadow-offset-y = -7;
shadow-opacity = 0.63;
shadow-exclude = [
"! name~=''",
"name = 'Notification'",
"name = 'Plank'",
"name = 'Docky'",
"name = 'Kupfer'",
"name = 'xfce4-notifyd'",
"name *= 'compton'",
"class_g = 'Conky'",
"class_g = 'Kupfer'",
"class_g = 'Synapse'",
"class_g ?= 'Notify-osd'",
"class_g ?= 'Cairo-dock'",
"class_g ?= 'Xfce4-notifyd'"
];
shadow-ignore-shaped = true;
menu-opacity = 1;
inactive-opacity = 1;
active-opacity = 1;
frame-opacity = 1;
inactive-opacity-override = false;
alpha-step = 0.06;
blur-background-fixed = false;
blur-background-exclude = [
"window_type = 'dock'",
"window_type = 'desktop'"
];
fading = true;
fade-delta = 3;
fade-in-step = 0.03;
fade-out-step = 0.03;
fade-exclude = [ ];
mark-wmwin-focused = true;
mark-ovredir-focused = true;
use-ewmh-active-win = true;
detect-rounded-corners = true;
detect-client-opacity = true;
refresh-rate = 0;
vsync = "opengl-mswc";
dbe = false;
paint-on-overlay = true;
sw-opti = true;
unredir-if-possible = true;
focus-exclude = [ ];
detect-transient = true;
detect-client-leader = true;
wintypes:
{
tooltip =
{
fade = true;
shadow = false;
opacity = 0.80;
focus = true;
};
};

P.S. On a machine with Intel integrated graphics on an i7 processor, nothing too fancy.

[richardgv]

Thanks for the report, firstly.

Unfortunately I have not being able to reproduce the issue with xfwm4, so far,
with compton-git-v0.1_beta2-51-g65e655e-2014-11-30, slightly modified version of your configuration file (vsync opengl-mswc -> opengl-swc, since my binary blob doesn't support the Mesa extension), firefox-34.0.5, rxvt-unicode-9.20. I tried changing themes to some other ones with different thickness of border, didn't help.

First thing I thought of is --xrender-sync and --xrender-sync-fence. With recent versions of xf86-video-intel you probably would need these options (see comments in #218). They are not available in stable release (0.1_beta2), and you would need a development snapshot (for example, from my PPA) to use them.

Another thing is --glx-swap-method. Improperly specified values may cause similar corruptions (or with --blur-background, but that's not your case). Try disabling it (or use undefined).

If neither suggestions help...

1. How is corruption occurring, Immediately after window creation, after an update of window content, or after a specific (series of) actions? Is there a way to reliably reproduce it, or it just appears random? Does it only occur on the bottom edge or all 4 edges? Does changing xfwm4 decoration style help (specifically, try the ones with different border thickness)? What if you disable shadows? Does launching compton manually (i.e. from a terminal) helps?

2. Does the problem appear if you run compton with:

   compton --config /dev/null --backend glx --vsync opengl-mswc
   compton --config /dev/null --backend glx --vsync opengl-mswc --paint-on-overlay
   compton --config /dev/null --backend glx
   compton --config /dev/null --backend glx --paint-on-overlay
   compton --config /dev/null
   compton --config /dev/null --paint-on-overlay
   

[bongochong]

Very strange. In regard to --xrender-sync / --xrender-sync-fence, I do use your PPA, so I have the latest build of Compton off there. Would I simply add both of those switches to my config file, or either one of them alone? Let me know and I'll try that out promptly. I also see some interesting stuff about --backend xr-glx-hybrid, do you think that would help my situation?

As far as --glx-swap-method goes, I tried using undefined and the issue still rears its head. To answer your questions anyway:

A. Corruption seems to occur both on window content updates and creation of new windows, though it does not seem to follow any pattern. The only way I can reliably reproduce it easily, is if I repeatedly open new Firefox or Xfce Terminal tabs and individual windows, then it will inevitably show up. Though like I said, the issue shows up in other applications too, just much less frequently. It only occurs on the bottom edge. Changing window decoration style doesn't make a difference, and neither does disabling shadows. Launching from terminal doesn't improve the situation either (in-fact, it gave the dotted lines / dashes a rather odd orange tint that I hadn't ever seen before). I did notice when using Compton from the terminal though, that it threw out some errors while using Thunar, Firefox and Mousepad. They were as follows:

restack_win(0x05800003, 0x05800040): Failed to found new above window.
restack_win(0x01400a6e, 0x05800040): Failed to found new above window.
restack_win(0x05800003, 0x05800040): Failed to found new above window.
restack_win(0x01401fc0, 0x05800040): Failed to found new above window.

B. The problem occurs when running Compton from the terminal simply via compton, and along with each of those switches you mentioned.

P.S. I just did some additional digging to see if maybe this is an Xfce issue on Intel graphics, and it seems that it could be, according to here: http://askubuntu.com/questions/312986/dashed-borders-of-my-window-manager-xfce I even tried using the suggestion there (changing acceleration from SNA to UXA), and while there wasn't any border corruption, it introduced a host of other issues (strange blurs during animated transitions, odd blue lines etc...). So, UXA acceleration is definitely not an option. Which now gives me the impression that maybe this isn't an issue with Compton. If that is so, is this an issue that changing my Compton settings could fix? Feeling a bit confused now.

[psamim]

I see the same thing only under the Firefox window and even when Compton is not running. I am just saying this in case it helps. I am using i3 and Compton in Archlinux.

[psamim]

My fault. In case anyone else ends up here by Googling, my dotted Firefox window border was because of Vimperator add-on. I added this to my .vimperatorrc:

highlight ContentSeparator border-top: 0px dotted gray; display: -moz-box;