Can't highlight part of text that is rendered as a ligature with the mouse

Migrated from https://bugs.launchpad.net/inkscape/+bug/1581275
No duplicates when searching for ligatures in https://gitlab.com/groups/inkscape/-/issues?scope=all&utf8=%E2%9C%93&state=all&search=ligature

Steps to reproduce:

• open Inkscape
• write some text, e.g. "unflattering"
• switch to a font where the fl is treated as a ligature (e.g. DejaVu Sans)
• try to highlight the l only, or put the cursor between the f and the l, without the keyboard

What happened?

• can't highlight just part of the ligature by clicking and dragging
• can't position cursor between the f and l by clicking
• both can be done with arrow key navigation, but when only one letter is highlighted, both appear to be highlighted anyway.

What should have happened?

• Inkscape treats the ligature as if it is two character. You should be able to select characters individually using the mouse.

Version Info:

• 1.1-dev (e4105d8b, 2020-11-20) Linux Mint 20
• 0.92.5 (0ad1ac96, 2020-08-06) Linux Mint 20
• trunk rev. 14902 Windows XP (32-bit)
• 0.91 Windows XP (32-bit)
• 0.91 r13725. Mac OS X 10.11.4.