The following minimal example contains two lineedits: After I change focus to the second one (e.g. by pressing Tab) I cannot enter accented characters into it (normal characters work).

The second line edit is a special one: It is wrapped by an outer widget (OuterEditor) which delegates focus to its inner lineedit. This is similar to a focus proxy. The reason that I do not use focus proxies is that in my real application OuterEditor should hide its inner lineedit until it receives focus (it will display something else when it does not have focus).