How to conceal multiple characters without making text dance upon hovering?

Question

Say that I have pattern aaaaapple in my text file, and say that I configured vim so that it conceals a\+.

What will happen is that, if conceallevel=1, then aaaaapple will become _pple. Note that aaaaa is replaced by a single space _ (I'm writing spaces as _ due to technical difficulties). This causes the line to jiggle/dance every time I hover on the concealed word, due to the single space _ expanding into 5 characters aaaaa.

What I want is to conceal aaaaapple such that it becomes _____pple instead of _pple. This way, when I move to the line where this conceal happened, the text won't jiggle/dance by expanding/shrinking. I.e. it looks like _____pple before hovering on it, and aaaaapple after hovering on it. No jiggling!

Any idea how to do this conceal such that each concealed character is replaced by a space (and not replacing all concealed characters by a single space)?

Answer 1

Instead of matching all duplicate "a"s in a single match, try concealing each extra "a" in its own, concealed group:

syn match HideAa "a\zea" conceal

Because this conceals only a single "a" with its own syntax group conceal, it will effectively apply a concealing space to each "a".

Answer 2

See :h concealcursor. It controls which modes will be activated for conceal. In this case you want to disable it for normal mode. I recommend trying setl concealcursor=vic