Is there a way to click a default button with the keyboard, without Full Keyboard Access? In Xcode when I go to commit files, I get a sheet with "Cancel" and "Commit" buttons, where the latter is the default (colored/pulsing) button.  I can hit Escape to Cancel, but I haven't found any way to Commit with just the keyboard.

In particular, pressing Return doesn't work.  There's a multiline text area on this sheet, so pressing Return adds a new line there.

In this question, the first answer suggested command + first letter (which would be command-C, which is Copy, as usual), and the second answer suggested turning on "Full Keyboard Access" (which I don't want).

Is there any way to click a pulsing default button with just the keyboard, without turning on Full Keyboard Access?  Or is the pulsing purely to indicate to me that it's the default choice that I should click to continue?
When the focus is on a multiline text view, pressing enter (⌤ or fn↩) usually selects the blue default button. (At least it does in some bug report dialogs.)