TabStrip.Count (gb.qt4)

Property Count As Integer

Returns or sets the number of tabs.

Warning...

Setting this value in the IDE will auto-name the tabs as Tab 1, Tab 2, Tab 3, etc

But setting it by code may not so you should supply the titles yourself.
If you do not the tabs could have no text so will be very small and impossible to see.

Ie..
  TabPanel1.Count = 2
  TabPanel1[0].Text = "Tab 1"
  TabPanel1[1].Text = "Tab 2"