I've attached a demo.
As a basis I have the project
\TMS VCL UI Pack\Demos\AdvOfficeMDITabSet is used.
I put a TADVOfficePager on the child form UOfficeMDITablePage.pas and compiled the project.
I open the child and hover over the tab headers, the tab headers flicker.
AdvOfficeMDITableSetDemo.zip (2.2 MB)