[Lazarus] Property ShowTabs of the component PageControl

[Junior]

Lazarus 1.1 r42622M FPC 2.6.2 i386-linux-gtk 2

The property ShowTabs of the component PageControl not drawing the 
screen in the Lazarus IDE.

The error occurs when it adds more than one page.

1 PageControl (add 2 tabsheet);
Add um button into tabsheet;
click on tabsheet navigating on them.

the button (or other components) disappears from the IDE.

Bug?