Transparency works fine for me (using cairo-compmgr 0.3.0) - see the attached screenshot.

[Original comment by snoggo@…]

Got the same problem here.
I'm running FreeBSD 8.0-p2, i3 2010-03-30, xcompmgr 1.1.5 and urxvt 9.07. (worked with xmonad)

inheritpixmap works fine but leaves ugly black borders.

If I could help you out with something, just tell me.

Replying to comment 2 by snoggo@…:

Got the same problem here.
I'm running FreeBSD 8.0-p2, i3 2010-03-30, xcompmgr 1.1.5 and urxvt 9.07. (worked with xmonad)

inheritpixmap works fine but leaves ugly black borders.

If I could help you out with something, just tell me.
With which options do you start xcompmgr? Can you provide a screenshot of the settings working (xmonad) vs. not working (i3)?

[Original comment by snoggo@…]

I've attached both screenshots.
Both times, I'm starting xcompmgr only with -n for simple client-side compositing.
Settings didn't change between screenshots. The only difference is that xcompmgr is called via .xinitrc in xmonad and via custom .startup in i3.

BTW: if I use transset-df, the transparency works well in i3. screenshot follows.

I can get it to work in i3 when using xcompmgr -c (shadows are visible immediately). Changing transparency with transset-df also works then. I am not very familiar with compositing but I don’t really see the issue here. Is using -n somehow important instead of using -c?

[Original comment by snoggo@…]

xcompmgr -c performs client-side shadows and fuzzy edges and enables transparency support. To use the transparency, I have to run transset-df on every window I open up.

xcompmgr -n performs full client-side compositing (which also includes transparency support). To use the transparency, I just have to tell urxvt to use the alpha channel in its background color.
This is what the [85] is for in my .Xdefaults.

Another downside of -c is that - using transset-df - the border also gets transparent. This isn't very important to me.

I'm not sure if it helps, but xprop -frame shows _NET_WM_WINDOW_OPACITY(CARDINAL) = 1288490188 for an urxvt which I made transparent using transset-df. This property is not set if the window isn't transparent. Seems to me that i3 doesn't handle some kind of window hint from urxvt and it works using transset-df because the whole window (including the frame/border) gets this hint.
Maybe I'm wrong, I'm not much into window handling ;)

Hm, I cannot get that to work in xmonad. I have an .xsession which looks like this:

xcompmgr -n &
sleep 1
exec xmonad

My .Xresources contains urxvt.background: [85]black (also note that comments start with !, not with #, so you might want to fix that in your .Xdefaults). When I start two urxvts, they are not transparent. Any hints on what to change to get it working?

[Original comment by snoggo@…]

Oh, I'll fix it, thank you :)

I'm not sure if urxvt.depth has something to do with it. Mine is at 32 which may be non standard. I also compiled it with support for xterm 256 colors and afterimage, don't know if thats important.
Which version of xmonad are you running? I was running 0.9.1.
Which distribution are you using?

You are right - the urxvt.depth: 32 was necessary to get it working. Let’s see if I can see what’s missing in i3 now…

Hm, seems like this is a problem which has to do with reparenting. I will have a look at it when I am at home again.

I tried to create the windows with argb visual, but that failed. This post might help, but no time to implement it right now:
http://efreedom.com/Question/1-3645632/Create-Window-Bit-Depth-32

Removing version 3.ε since this affects all versions of i3

I think this is fixed with the changes we had with 32 bit visuals.