Clear to end of line uses the wrong background color in tmux

Question

In ZSH prompt expansion, the command %E is supposed to "Clear to end of line."

This works:

However, it does not work in tmux:

The issue seems to be with BCE (Background Color Erase). In screen, I can add the option defbce on. I can't find any similar setting for tmux. Does it exist?

Answer 1

Unlike screen, tmux does not have switchable background colour erase capability in its terminal emulator. Erasure is always with the default background colour, never the current background colour.

Nicholas Marriott added it to the to-do list in September 2015, but stated at the time that neither he nor anyone else cares enough about it to implement it.

He later implemented it in October 2016, nearly a year after this answer was originally written.

Further reading

• Nicholas Marriott (2015-09-15). Support background color erase (bce). tmux/tmux. Bug #109. GitHub.
• Nicholas Marriott (2015-09-15). Add BCE to TODO.. tmux/tmux. 54bd7612868341c47bd3bd237c9598d5860b3ef3. GitHub.
• vim colorscheme completely wrong inside screen or tmux sessions:

t_ut turns off BCE. tmux should support BCE but it depends on the tmux version, I think 2.1 is too old.