Hi Peter,
You could handle the XPTaskBarBox''s CollapsedStateChanged event for this purpose. I have modified the XPTaskBar sample present in the folder - ..\Syncfusion\Essential Suite\Tools\Samples\GroupBar Package\XPTaskBar as per your specifications above :
Modified_XPTaskBarSample_Application_1197.zip. When you collapse/expand the lower XPTaskBarBox, you could observe that the appropriate messages are displayed and when expanded the focus has been placed on the ''Keyword'' TextBox. Please take a look at the sample and let me know if this helps. Thanks for choosing Syncfusion products.
Regards,
Guru Patwal
Syncfusion, Inc.