[Lazarus] TPageControl.TabVisible not working properly

[Daniel Gaspary]

The bug #0021723 is still happening even after the related
issue(#23251) appears to be patched.

To test:

-Create a project with a TPageControl

-Create two Pages

-Put a TLabel on each page

-On formcreate set TabSheet1.TabVisible to false;

When the program is running the tab shown is the second, but the
contents are from page 1.

(Windows XP 32 bits)