Looks good! Thanks.

...

While "rainbow colours" sounds nice "Bracketcolors" is more descriptive, so a user looking for it is more likely to find it.

Full agree. @asifamin13 maybe you could just mention "rainbow colors" in the README, that might already suffice that users can find it also with this name.

I did a quick code review without having a deeper look at the logic. From a quick test, it works as advertised and I got many fancy brackets :).

A few comments @asifamin13:

• Could you add the plugin name in https://github.com/geany/geany-plugins/blob/master/build/geany-plugins.nsi#L... (this is for the Windows installer, use `bracketcolors.dll`)
• As Geany itself also colorizes the brackets in an idle callback, did you check that both implementations do not interfere with each other?
• I got a few compiler warnings which might be worth looking into:

BracketMap.cc: In member function 'void BracketMap::Show()':
BracketMap.cc:122:21: warning: loop variable 'it' creates a copy from type 'const std::pair<const int, std::tuple<int, int> >' [-Wrange-loop-construct]
  122 |     for (const auto it : mBracketMap) {
      |                     ^~
BracketMap.cc:122:21: note: use reference type to prevent copying
  122 |     for (const auto it : mBracketMap) {
      |                     ^~
      |                     &
bracketcolors.cc: In function 'gboolean utils_parse_color(const gchar*, GdkColor*)':
bracketcolors.cc:276:27: warning: 'gboolean gdk_color_parse(const gchar*, GdkColor*)' is deprecated: Use 'gdk_rgba_parse' instead [-Wdeprecated-declarations]
  276 |     return gdk_color_parse(spec, color);
      |            ~~~~~~~~~~~~~~~^~~~~~~~~~~~~
In file included from /usr/include/gtk-3.0/gdk/gdkcairo.h:26,
                 from /usr/include/gtk-3.0/gdk/gdk.h:33,
                 from /usr/include/gtk-3.0/gtk/gtk.h:30,
                 from /home/enrico/apps/include/geany/gtkcompat.h:30,
                 from /home/enrico/apps/include/geany/editor.h:27,
                 from /home/enrico/apps/include/geany/document.h:31,
                 from /home/enrico/apps/include/geany/build.h:26,
                 from /home/enrico/apps/include/geany/geanyplugin.h:36,
                 from bracketcolors.cc:40:
/usr/include/gtk-3.0/gdk/deprecated/gdkcolor.h:79:11: note: declared here
   79 | gboolean  gdk_color_parse     (const gchar    *spec,
      |           ^~~~~~~~~~~~~~~

Thanks for the feedback!

- The deprecated `gdk*` warning are ok. I removed the unused debugging code that was causing the others. - I added the bracketcolors entry to `geany-plugins.nsi`. - I confirmed my plugin behaves correctly when Geany colors brackets itself, like when brackets are missing