I can't reproduce this.  It doesn't give great feedback when you give it a bogus
theme, but it doesn't crash.  What's the tarball you have?

I was taking another look at it and i think it crashes when you select a theme
that uses a not installed engine. Try Etria.org found at art.gnome.org.

I can't reproduce this.  It doesn't crash for me.  Can you confirm that that's
the tarball that causes the crash for you?

Confirmed, and other tarballs found at art.gnome.org makes it crash too.
The themes i have installed:
Bluecurve
Bluecurve-blue
Bluecurve-Okaysh
Metal
Raleigh
Redmond95

Maybe on of this installed themes is causing the crash?

I can't reproduce this at all.  I'm able to drag a URI from mozilla to the theme
manager and have it install fine.  Which version do you have?  Can you get a
backtrace at all?

These are the last messages using strace:

read(3, "\1\2\241 \0\0\0\0\363\4@\3\0\0\0\0\0\0\0\0\1\0\0\0000\204"..., 32) = 32
write(3, "+\10\1\0", 4)                 = 4
read(3, "\1\2\242 \0\0\0\0\363\4@\3\0\0\0\0\1\0\0\0\1\0\0\0000\204"..., 32) = 32
poll([{fd=6, events=POLLIN}, {fd=3, events=POLLIN}, {fd=10, events=POLLIN},
{fd=12, events=POLLIN|POLLPRI}, {fd=13, events=POLLIN|POLLPRI}, {fd=14,
events=POLLIN|POLLPRI}, {fd=15, events=POLLIN|POLLPRI}, {fd=17,
events=POLLIN|POLLPRI}, {fd=16, events=POLLIN|POLLPRI}, {fd=20, events=POLLIN}],
10, 0) = 0
ioctl(3, 0x541b, [0])                   = 0
ioctl(3, 0x541b, [0])                   = 0
poll([{fd=6, events=POLLIN}, {fd=3, events=POLLIN}, {fd=10, events=POLLIN},
{fd=12, events=POLLIN|POLLPRI}, {fd=13, events=POLLIN|POLLPRI}, {fd=14,
events=POLLIN|POLLPRI}, {fd=15, events=POLLIN|POLLPRI}, {fd=17,
events=POLLIN|POLLPRI}, {fd=16, events=POLLIN|POLLPRI}, {fd=20, events=POLLIN}],
10, 0) = 0
--- SIGSEGV (Segmentation fault) ---
write(3, "\33\10\2\0\0\0\0\0 \5\2\0\0\0\0\0+\5\1\0", 20) = 20
read(3, "\1\2\245 \0\0\0\0\363\4@\3\0\0\0\0\0\0\0\0\1\0\0\0000\204"..., 32) = 32
clone(child_stack=0, flags=0x1200011)   = 2697
wait4(2697, [WIFEXITED(s) && WEXITSTATUS(s) == 0], 0, NULL) = 2697
--- SIGCHLD (Child exited) ---
sigreturn()                             = ? (mask now [SEGV])
SYS_252(0x1, 0x3d5f, 0x5503a290, 0x81bb1af, 0x8052ec6

I was testing it again, and it fails for every theme i try to add.
I have tried with another user too (to use another config) but it crashes
the same way.

Hi,
I'm going through bugs assigned to me and attempting to clean some of the older,
fixed ones up.

This bug hasn't changed in over a year old now.  Are you still seeing the problem? 

(This a batch message is being sent to all my bugs that haven't changed in a year)

Hi,

This bug has been in the NEEDINFO state for at least a couple of weeks now.  I'm
going to close the bug, but if you can provide the required information feel
free to open a new report.

Thanks.

(This is a mass message being sent to a bunch of bug reports)