This can be done with the [GeanyLua](https://plugins.geany.org/geanylua/) plugin. Here is a script that implements the feature: [column-markers](https://github.com/xiota/geanylua-scripts/tree/main/column-markers). You can add as many column markers as you like.
The script sends messages to scintilla: ```lua -- set multiple column marker mode geany.scintilla ("SCI_SETEDGEMODE", 3, 3)
-- clear current markers geany.scintilla ("SCI_MULTIEDGECLEARALL", 0, 0)
-- add new column markers, colors are in BGR order geany.scintilla ("SCI_MULTIEDGEADDLINE", 60, 0xe5e5e5) geany.scintilla ("SCI_MULTIEDGEADDLINE", 72, 0xf0c098) -- blue geany.scintilla ("SCI_MULTIEDGEADDLINE", 80, 0xdd8add) -- purple geany.scintilla ("SCI_MULTIEDGEADDLINE", 88, 0xe5e5e5) geany.scintilla ("SCI_MULTIEDGEADDLINE", 96, 0x5161f6) -- red ```
Each document maintains it's own set of markers, and new documents are created with the default Geany marker. So the script needs to be run for each document. This can be done by editing [event scripts](https://plugins.geany.org/geanylua/geanylua-intro.html) located at `~/.config/geany/plugins/geanylua/events`. I've found that `activated.lua` is currently the best script to use for this. To apply the setting to documents when Geany is first started requires signals that GeanyLua doesn't currently handle ([geany-plugins#1112](https://github.com/geany/geany-plugins/pull/1112)).