Ismael Asensio authored Feb 13, 2022 and Nate Graham committed Mar 07, 2022

Apart from a minimum logic refactor, this introduces two fixes:
- Only affect custom header visiblity for current page
- Do not set customHeader text when not visible

When calling `KTitleWidget::setText()`, this would set the custom
header visible again. So do it only if we want it actually visible.


(cherry picked from commit 1022d0b0)