Or maybe to explain a little more clearly - my workflow there was either:

Type a comment > select icon > tab > tab > enter

or

Select icon > tab > type comment > tab > enter

depending on whether I felt more inspired by icons or words first, lol. Right now, it's:

Type a comment > select icon > tab > the tab moves the cursor to the top of the screen somewhere > scroll down > click into the text box again out of habit > tab > enter

or

Select icon > tab > the tab moves the cursor, as discussed, into space > scroll down > click into the text box > type a comment > tab > enter

to complete the posting process.