setThumbnailYalign
Sets the vertical alignment of the thumbnail for @self.
If the page is so tall that class@TabOverview can't display it completely and has to crop it, vertical alignment will determine which part of the page will be visible.
For example, 0.5 means the center of the page will be visible, 0 means the top edge will be visible and 1 means the bottom edge will be visible.
The default vertical alignment is 0.
Since
1.3
Parameters
yalign
the new value