I’ve installed Ubuntu MATE on someone’s computer today and spent a little time with her walking through basic familiarization and customization.
I think that we should list Firefox Keyboard shortcuts in welcome too, at least for the common ones that are also cross-browser such as:
CTRL + T Create a new tab
CTRL + T then TAB Create a new tab and position yourself for a google search
CTRL + W Close current tab
CTRL + SHIFT + T Open last closed tab
CTRL + TAB Rotate between tabs
CTRL + SHIFT + TAB Rotate between tabs backwards