There's a lot of output from the debug build to the console, this goes on forever: nsLineLayout: ButtonControl(input)(-1)@0xa955ef4 metrics=480,23065185! ###!!! ASSERTION: bad height: 'Not Reached', file /builds/firefox-1/mozilla/layout/generic/nsLineLayout.cpp, line 253 Block(select)(0)@0xa955c18: Init: bad caller: height WAS 23065095(0x15ff207) ###!!! ASSERTION: bad height: 'Not Reached', file /builds/firefox-1/mozilla/layout/generic/nsLineLayout.cpp, line 253 ComboboxControl(select)(1)@0xa956350: Init: bad caller: height WAS 23065155(0x15ff243) nsLineLayout: ButtonControl(input)(-1)@0xa992e58 metrics=480,23065215! ###!!! ASSERTION: bad height: 'Not Reached', file /builds/firefox-1/mozilla/layout/generic/nsLineLayout.cpp, line 253 Block(select)(1)@0xa992d38: Init: bad caller: height WAS 23065125(0x15ff225) ###!!! ASSERTION: bad height: 'Not Reached', file /builds/firefox-1/mozilla/layout/generic/nsLineLayout.cpp, line 253 ComboboxControl(select)(0)@0xa8d6cbc: Init: bad caller: height WAS 23065185(0x15ff261)

The reflow log shows this repeating(with slightly different values) block 0x9ba9d10 r=0 a=200,285 c=UC,UC cnt=236 text 0x9ba9d64 r=2 a=200,UC c=UC,UC cnt=237 text 0x9ba9d64 d=60,255 me=60 block 0x9ba9d10 d=200,285 me=120 select 0x9c54750 r=2 a=500,UC c=500,UC cnt=238 select 0x9c54750 r=2 a=500,UC c=500,255 cnt=239 area 0x9c54930 r=2 a=495,UC c=UC,UC cnt=240 area 0x9c54930 d=0,0 select 0x9c54750 d=530,285 select 0x9c54750 d=530,285 area 0x9c54664 d=500,345 area 0x9baa448 r=0 a=UC,UC c=UC,UC cnt=241 select 0x9baa520 r=0 a=UC,UC c=UC,UC cnt=242 select 0x9baa520 r=0 a=UC,UC c=UC,UC cnt=243 area 0x9baa64c r=0 a=UC,UC c=UC,UC cnt=244 text 0x9c572d4 r=0 a=UC,UC c=UC,UC cnt=245 text 0x9c572d4 d=0,0 me=0 area 0x9baa64c d=0,0 me=0 select 0x9baa520 d=30,30 me=30 select 0x9baa520 r=2 a=UC,UC c=0,255 cnt=246 area 0x9baa64c r=2 a=0,UC c=UC,UC cnt=247 area 0x9baa64c d=0,0 select 0x9baa520 d=30,285 select 0x9baa520 d=30,285 area 0x9baa448 r=0 a=330,345 c=270,285 cnt=248 block 0x9c57428 r=0 a=330,UC c=UC,UC cnt=249 text 0x9c5747c r=0 a=330,UC c=UC,UC cnt=250 text 0x9c5747c d=60,255 block 0x9c57428 d=330,285 button 0x9c57548 r=0 a=330,UC c=0,120 cnt=251 button 0x9c57548 r=0 a=330,UC c=240,285 cnt=252 area 0x9c57608 r=0 a=150,UC c=150,UC cnt=253 text 0x9c576f0 r=0 a=150,UC c=UC,UC cnt=254 text 0x9c576f0 d=0,0 area 0x9c57608 d=75,0 button 0x9c57548 d=480,345 button 0x9c57548 d=480,345 area 0x9baa448 d=870,345 o=(0,0) 870 x 413 I can attach the full log if that would be useful.

Might be the same as bug 348991.

Hangs 2006-12-07 but not 2006-12-08. (Mac trunk nightlies) -> FIXED by reflow branch landing.

I checked in a crashtest a few days ago.