Incorrect font rendering with SDL2

[mychris]

Ligatures are rendered differently, dependent on line-wrapping and the current cursor position. In the first picture, line-wrapping is enabled, in the second disabled:

This happens only for the line the cursor is currently on. If line-wrapping is disabled, ligatures are no longer rendered as a single glyph for the line the cursor is on.

There is also a problem with non monospace fonts, which are outlined with kerning.
The following picture is an example with the Caveat font (https://fonts.google.com/specimen/Caveat):

If line-wrapping is disabled, it gets ever worse:

While this might not be a problem with monospace fonts and normal or bold rendering, but if italics are added, this will most likely appear there as well.

[mychris]

The problem here is, that the backend splits up a line into multiple text objects, dependent on text-attributes and cursor position. If line-wrapping is disabled, the backend creates one object for every character. The frontend can then no longer render these objects together, or would have to merge them again, to ensure correct rendering of the text.