It seems sideways-lr text frames have a larger than normal overflow area. This additional area has the same size as the overflow area the text frame should have normally. This additional overflow area doesn't cause any observable rendering difference, so it is probably not a big deal, but we probably want to fix it at some point.
Created attachment 8740222 [details] [diff] [review] patch for showing the overflow area This patch adds code to text frame painting to render a translucent red rect covering the overflow area.
Created attachment 8740223 [details] [diff] [review] patch for showing the visual overflow area
Attachment #8740222 - Attachment is obsolete: true
Created attachment 8740225 [details] testcase This is the testcase file for comparing the visual overflow area.
Created attachment 8740226 [details] screenshot Screenshot of the testcase page with a patched build.
FWIW, you can see this without needing a special patched build, if you just enable nglayout.debug.paint_flashing and then watch what gets repainted when selecting text in your testcase, for example.
Per policy at https://wiki.mozilla.org/Bug_Triage/Projects/Bug_Handling/Bug_Husbandry#Inactive_Bugs. If this bug is not an enhancement request or a bug not present in a supported release of Firefox, then it may be reopened.
Status: NEW → RESOLVED
Last Resolved: 2 days ago
Resolution: --- → INACTIVE
You need to log in before you can comment on or make changes to this bug.