Fix middle click on sidebar tab bar unloads the document.

Filter the exact widget we care about for middle mouse buttons

BUGS: 426613
5 jobs for !304 with work/aacid/426613 in 55 minutes and 29 seconds (queued for 652 minutes and 52 seconds)
detached
Status Job ID Name Coverage
  Build
passed #74725
build_clazy_clang_tidy

00:16:45

passed #74723
build_ubuntu_18_04

00:11:11

passed #74724
build_ubuntu_20_04

00:14:25

passed #74726
clang_format

00:01:20

passed #74722
linux kf5-qt5 qt5.12

00:11:46

44.0%