Calling wxDialog::EndModal() directly from inside the dialog is a
potential bug if the dialog is shown in the modeless or window modal
(quasi-modal). Use the internal button events where possible and
check for the appropriate mode before calling the correct end dialog
function.
It's tempting to say that we don't need to exclude filename chars
from symbols, but we might regret that decision down the road. Better
to just escape them.
Fixes https://gitlab.com/kicad/code/kicad/issues/8694
Wayne Stambaugh
Jeff Young