Not displaying descenders and underscore in Wikipedia edit summary

[ari5_96]

I have a couple of problems with the rendering of text in the "Edit summary" field when editing pages on Wikipedia using Wikipedia's MonoBook skin. In particular:
- The descenders (those parts of letters "below the line", eg on "g", "y") and underscore characters are not visible on the text.
- The caret (typing cursor) disappears when the text reaches the right side of the field, near the characters-remaining count.

A discussion at https://en.wikipedia.org/wiki/Wikipedia ... t/headline describes the problem, and how it seems to be dependent on combinations of various things, but I've managed to narrow it down and reproduce it reliably thus:

On Windows 7 SP1 Ultimate or Windows 10 Pro version 1709, both 64-bit...
Using a new Windows user account, so that the default Windows settings are used (in case it matters)...
Install Pale Moon 27.x.x, 64-bit, and use a new PM profile with default settings.
Maximize the PM window (but also see below)
While not logged in to Wikipedia, go to the web page https://en.wikipedia.org/w/index.php?ti ... n=monobook, click "Start editing" if the "Welcome to Wikipedia" pop-up appears, then type something in to the Edit summary at the bottom - include letters with descenders and underscores to observe their non-display. Keep typing until the text approaches the decrementing counter on the right, and observe the caret disappear - note that you can still type more characters (unless you have a very wide screen).
A variation on this is that if I do not maximize the PM window on the screen, then scroll up and down using the PM windows scroll bar, sometimes the edit summary text displays descenders and underscores, and sometimes the caret is displayed correctly on the right edge (before the counter) of the text box, mostly when the edit summary text is displayed closer to the bottom of the PM window.

(The edit URL is Wikipedia's sandbox, so it doesn't matter if you click "Publish changes". The "&useskin=monobook" is required to force the MonoBook skin - the default skin is usually.)

I haven't tested every version of PM, but the text displays OK with v25.0.2, 26.0.3, 26.5.0, and fails on 27.0.0, 27.0.2, 27.6.2

For comparison:
FireFox 57.0.2 (64-bit, default FF profile) displays descenders and underscores correctly on both Windows 7 and 10, but not the caret on the right edge of the text box.
Internet Explorer 8 (as included in Windows 7 SP1) displays descenders and underscores correctly (and handles the right edge of the edit box badly).
Microsoft Edge (as included in Windows 10) displays everything correctly.
Google Chrome Portable 52.0.2743.116 (32-bit, default profile) running on Windows 7 or 10 displays everything correctly.

The above specific tests were done in a VirtualBox virtual machine (running on Windows 7 Pro SP1 64-bit host) to give a consistent reproducable environment. I can also replicate the problem on the physical machine in my normal customized environment, and also in a newly created Windows account with default Windows profile and default PM profile on the host machine.

[ari5_96]

A discussion at https://en.wikipedia.org/wiki/Wikipedia ... t/headline describes the problem

The Wikipedia discussion has been archived (again) but should be permanently visible at https://en.wikipedia.org/wiki/Wikipedia ... t/headline.