Is there a bookmarks feature in Geany?

This is the normal way to create bookmarks in Geany:

Bookmarks

Geany provides a handy bookmarking feature that lets you mark one or more lines in a document, and return the cursor to them using a key combination.

To place a mark on a line, either left-mouse-click in the left margin of the editor window, or else use Ctrl-m. This will produce a small green plus symbol in the margin. You can have as many marks in a document as you like. Click again (or use Ctrl-m again) to remove the bookmark. To remove all the marks in a given document, use "Remove Markers" in the Document menu.

To navigate down your document, jumping from one mark to the next, use Ctrl-. (control period). To go in the opposite direction on the page, use Ctrl-, (control comma). Using the bookmarking feature together with the commands to switch from one editor tab to another (Ctrl-PgUp/PgDn and Ctrl-Tab) provides a particularly fast way to navigate around multiple files.

Source

To add a list of these bookmarks, you have to install the Geany plugin "Addons":

sudo apt-get install geany-plugin-addons

To remember the bookmarks at each file load, the plugin "Numbered Booksmarks" is required:

sudo apt-get install geany-plugin-numberedbookmarks

(You have to save the file if you want save the bookmarks.)

After the installation, enable the plugin to load at startup:

Next step: Activate the bookmarklist -

Bookmarklist example: