FWIW, I get the same behavior as Mahāgaja mentions -- hitting the tab key just causes the cursor to jump from the main editing textbox to the Edit summary textbox. I cannot enter a tab at all in any Wiktionary edit field. The only way I can enter a tab is to copy-paste from some other application.
Could it be that I'm using the special module editor? I get the behaviour you describe when editing normal pages, but I don't need to type tabs there. When editing modules, I can type tabs.
