I am sorry if this message will not jump into necessary thread. I'm replying to digest message in Gmail and setting appropriate subject.
A little googling showed me, that this feature is in Geany wishlist. So, I
wish to implement it. After the brief investigation I've found, that it may be implemented in on_update_ui (src/editor.c) by checking active lexer, and if it is HTML, then calling editor_highlight_html_tag function (or something like this).
You should do language specific stuff in a plugin, you can connect to the editor-notify signal. Just ensure you return false.
Is it OK to implement on the editor level, or you think it would be
to implement on the Scintilla lexer level (LexHTML.cxx)? Please, suggest.
I assume you want to make it work like brace matching, when the cursor is in/next to a tag highlight the opposing tag.
It is probably not possible to implement in the lexer as it won't be called for changes to the cursor position.
Ok, I will implement it as a plugin. Thank you for the tips!