Comment 8 for bug 1271883

I personally think that this is a design decision and that this is rightfully so. Who on earth would *need* to increase their amount of workspaces by so much that they'd need to type in there? Don't forget: updating this setting takes effect immediately so typing e.g. a few numbers to many (instead of going for "11" you go for "111" or even "1111") ends up creating all those workspaces on the fly.

So I think it's actually safer to just increase the value step by step. Whoever wants to bump their workspace amount to an insanely high number (which would take too much time with the spinbuttons) can do so via xfconf-query or even via the GUI of xfce4-settings-editor.