First Tabsheet in Pagecontrol overlaps with tabs

[aquila]

When I create a pagecontrol (design view or runtime) and I add an tabsheet to this control, then the surface of this tabsheet overlaps with the tabs because its position is incorrect.
However when inspect the Top-property of the tabsheet then the function returns 0. So it should be located at its normal position which is just below the tabs.
The strange thing is that this problem is only present when I use Windows. When I switch to Linux or Mac the tabsheets behave correct.

I found a work around by setting the Top-value of this tabsheet to a arbitrary number and then setting it back to zero, but this only works the first time. If I remove all the tabs from the pagecontrol and add new ones to it, then the same problem arises, but the workaround doesn't work anymore.

Does somebody experience this same problem and knows how to solve it?

[alfadaemon]

On design time everything works great. But when I run the app, the firsts time the window/form with the page control appears correctly, but when I close it and open it again, nothing appears but the form. No page control or tabs are displayed.

What I use:

Ubuntu 7.04
Lazarus 0.9.22
fpc 2.0.4