Version-Release number of selected component (if applicable):
libreoffice-5.0.5.2-2.fc23.x86_64
gtk3-3.18.7-2.fc23.x86_64

How reproducible:
always

Steps to Reproduce:
0. log in to a gnome+wayland session
1. make sure you are running libreoffice with Gtk+ 3.x
2. open any Libreoffice Calc document
3. edit any cell
4. type "=S" or anything else which has autocompletion, probably everything starting with "="

Actual results:
In "Formula Bar" you see the function you just started typing. You'll get a hint for function names. This hint is misplaced, most times right outside the right top corner. It blocks keyboard input in the same ways X11 menus used to grab all input.

Expected results:
function suggestion should not block input and should be placed right below  the "Formula Bar" Toolbar.