selection moves some lines up by a pixel

[Bogdan Butnaru]

Binary package hint: firefox

This is on Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.2) Gecko/20061201 Firefox/2.0.0.2 (Ubuntu-feisty) --- exactly what the Feisty repositories gave me. apt-get calls it version 2.0.0.2+1-0ubuntu1.

Quite recently --- one or two updates ago, I think --- I noticed that in some places, selection moves characters around. As a simple example, go to http://en.wikipedia.org/wiki/Dns (you'll be redirected, that's OK). You'll get to the disambiguation page.

Put your mouse cursor on the "Did not start" line, press the left button and select up to the middle of the great "(disambiguation)" sign on top of the page. What should happen is that when they are selected, the first line starting from the "- Internet sys..." up to its end, and the entire "(Redirected from Dns)" line, will get translated upwards by a pixel.

If you deselect by just clicking on a blank space, the text is restored. If you started a selection but didn't release the button, and you "uncover" a selected line that has the bug, sometimes it's left moved by a pixel, sometimes it's normal.

The funny thing is that the bug in canceled (the text is drawn correctly) the moment the window looses focus. For some reason, this means that you can't screenshot the bug. It's fixed right before taking the screenshot...

I could send photos if you can't reproduce, but it's kind of hard to see.

[Bogdan Butnaru (bogdanb)]

I noticed it doesn't happen only for selection. The attached screenshot shows it occurring on the tab bar, which means it affects chrome too.

I use tabbrowser extensions to move the tabs on the bottom and select them on hover, so I'm not sure if this particular thing appears with normal FF. It happened when the tooltip appeared on the tab (by holding the mouse over). It was only visible when the tooltip disappeared.

The edge of the error is exactly where the tooltip started. If I make another tooltip appear to its right, the error remains there (but only if I don't change the tab). If I make one appear to the left, the error is extended to the entire area covered by the tooltip.

This also disappears if I try to make a screenshot.

[Bogdan Butnaru (bogdanb)]

Just for the record, I have seen this affect text input areas too, and icon/images. I can't figure out exactly the situation when it happens. (For instance, in the wiki link above, this doesn't appear without the stylesheet.) It also happens irregularly in the very text field I'm writting this text in (some lines move up or down while I write things, use backspace to delete things, or select parts of the text).

For instance, when I wrote the "t" after "backspace", that line and the one above it moved up by a pixel. It came back if I backspaced over it. It happened with any letter, and it is consistent (I cut to clipboard all the text up to there and tried repeating the type, it happens all the time.) But that particular position is not special in any way that I can tell. On my computer "things," was the first word on the line, so it was the first letter of the fourth word on the line, far from the line's end... I tried appending an "a" to backspace and the pattern changed.

[Bogdan Butnaru (bogdanb)]

This stopped happening a while ago, marking invalid.