I´ve installed LiveHTTPheaders extension. When I´m looking at Headers tab in PageInfo of this website, the separator between the two fields is moving up and down for 1 lineheight about twice a second, making my mozilla rather unresponsive for copy&paste and switching tabs. Celeron 333 with 96 MB of RAM, Screen resolution 800x600 Mozilla Build ID 2003081809. I´ve seen this already in http://mozdev.org/bugs/show_bug.cgi?id=3603 I´ve seen this also in a mail bug, in bug 201460 comment 2 Bug 201460 [Fix] Horizontal splitter vibrating by 1 char height I´ve seen this with Mozilla 1.4b BuildID 20030408 and LiveHTTPheaders 0.4 now I´ve got Mozilla 1.5b BuildID 2003081809 and LiveHTTPheaders 0.6 neil@parkwaycc.co.uk told about a working fix in bug 201460 comment 6

Steps to reproduce: 1. Install LiveHTTPHeaders http://livehttpheaders.mozdev.org/ 2. open http://www.eneco.nl/ in another tab 3. open PageInfo 4. Mouse over the Header tab, until the vibration is self-sustaining AT first, the movement is only short and stops, but when you got the right delay to restart that movement the oscillation starts. If I can take screenshots of the phases I´ll attach them here.

forgot to mention: Page info is full screen, 800x600 screenshots of field Headers installed by extension LiveHTTPHeaders. 1st screenshot: upper field contains 10 lines, lower field 7 lines, for a total of 17 2nd screenshot shows 9 and 8 lines respectively. The display toggles between these two states, on a Celeron 333 slower than on a XP1600. On the XP1600 the oscillation started immediately, on the celeron I had to wait some time, or move the mouse. It doesn´t matter, if there is only this one page open in a tab, or some tabs more. It doesn´t matter, if I use http://www.eneco.nl/ containing a flash ad, or if I use http://www.eneco.nl/engels/ containing no flash. It also doesn´t matter if flash plugin is installed (It wasn´t on the Athlon XP1600).

If I open the "Save As" box and resize it, so that it overlays most of the screen, the flickering frequency gets higher on my slow Celeron. I can resize it, that only the scrollbars at the right are visible, or the lowest 2 lines of the lower field, and it gets very fast. If I resize it so that only the lower field is hidden, I can stop the toggling, and can change the toggle states with a mouseclick.

I can reproduce this, following Hermann's steps, but with classic skin, not modern.

see also #205464 there's tons of dups on this.

WFM LiveHTTPHeaders 0.6 and Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.5b) Gecko/20030911, bug 201460 comment 2 was also wfm today. will retry with 1.4.1

WFM Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.4.1) Gecko/20030906 in comment #1 steps to reproduce I wrote: 4. Mouse over the Header tab, until the vibration is self-sustaining I remember that hovering over the tabs in the PageInfo window produced some visble reaction, now not anymore. I´m resolving this bug as wfm, as the only change seems to be in Mozilla. Livehttpheaders is unchanged, I suspect the website is unchanged, and I couldn´t reproduce this using the steps in bug 201460 comment 2 Seems to be fixed in Trunk and 1.4.1