As an openbox user (Crunchbang ‘Waldorf’) myself, I always like to open links from other applications in Chromium but it tends out open in Firefox. Checking out from the settings page of Chromium displays this message under ‘Setting default browser section’
"Chromium cannot determine or set the default browser"
Making Chromium or Chrome your default browser when not using one of widely/popularly used desktop environments such as Gnome, KDE, XFCE etc, becomes very difficult at times.
I fixed this problem by running the command below, which made chromium run is if it was a Gnome session, which enables the “Make Chromium my default browser” button (As shown in Fig. 2):
NOTE: All running sessions of Chromium or Chrome should be closed before running the command above.
Click Set as default and you’re done!
You can now open links from other applications in Chromium after clicking.