When using Gnome Wayland on F29 and using a keyboard layout with dead keys, for example “English (US, intl., with dead keys)” the preëdit shown by ibus
when a dead key is pressed is hard to remove.

For example, when using “English (US, intl., with dead keys)”, typing

   "a

results in 

   ä

While the a is not yet typed, the " is shown in preëdit, i.e. underlined.
If one now types BackSpace to remove the " and the preëdit because
one changed ones mind, the preëdit does not disappear. Instead it moves left when typing more BackSpaces and right when typing spaces. Typing an a now results in the a being inserted to the left of the " in preëdit and the preëdit moves right.

I found it quite hard and not obvious to get rid of that sticky preëdit.
I switch to the Japanese input method ibus-kkc and typed some Japanese, then came back to the “English (US, intl., with dead keys)” layout. Now the preëdit was gone but I still could not type "a to get ä anymore.

Fujiwara San told me the workaround to get rid of the preëdit, 
I have to type a dead key sequence again, then the preëdit disappears and the dead key sequences work again.

This is very confusing, therefore I think it is worth backporting that fix to F29.

(The problem occurs only in Gnome Wayland, it works fine on Gnome Xorg).