Display of unicode characters depends on characters around it
I’m not sure who to throw this issue at, but how unicode characters are displayed can depend on the characters around it in Notepad++. The following screenshot probably explains it best.
The display of the entire block or list of characters in non of these six examples is exactly the same.
Also, if you copy and paste example 4 onto a new line and you start deleting characters from the start of the line, you can see characters, even several positions to the right of the start, pop in and out of getting substituted by the “character unknown” character (a square with a question mark).
Did you report it at the issue board?
Make the demo file available.
Does it work better on older versions?
If you can test old versions and pin point a version where it broke it would probably help a developer take it from there.
It may be a Scintilla issue. I tried showing these symbols in SciTE under Linux (version 3.3.5) and it took some effort to make it show these symbols correctly. The key property I needed to modify was:
Not sure what exactly does it mean.
I’ve had this exact problem for months. If a displayable Unicode character is added to a line containing undisplayed Unicode characters, those “undisplayed” ones suddenly appear. Removing the “good” one makes the others revert to the hollow square. A simple example:
Paste that line into NP++ and you will see all the characters. Remove the leading star ☆ and the others become squares. Restore the star and the others re-appear.