The indicators will be truncated when viewing a same buffer on multiple windows

[hchbaw]

The indicators will be truncated sometimes on the inactive windows.

For example: Open the 'subr.el', goto end-of-buffer, split the window and make the above window active. Then scroll-up and down a bit for each window to view the different part of the same file.

The below window does not have enough indicators:

[hchbaw]

Note that the above commit is somewhat brute-force way. I cannot find any better ways... So, plese take this commit as some kind of proof of concept, feel free to throw away.

[jmickelin]

Merged your fix for now. I thought the window overlay property would prevent these things, but apprarently not.