Zend certified PHP/Magento developer

xfce: make dead keys invisible / disable preview

It used to be that dead keys, when using the Spanish layout, were actually “dead”. That is, nothing would show up until I typed the second key. Recently, however, I noticed that upon hitting a dead key (e.g. a diacritic) it shows a preview of the diacritic with a sort of placeholder, which gets replaced by the accented letter once I press the second key.

This is annoying and distracting. I’m already used to not seeing the dead keys and the visual feedback makes me think I mistyped.

How can this be turned off? I’m using XFCE if that matters.