alignByBaseline
Puts the child on the row's shared text baseline, which is what a label beside a text field sits on. Every child declaring it is placed so that its FirstBaseline falls on one line. A row asking for its own height holds the deepest baseline above that line and the deepest remainder below it. A line a Layout child's policy provides places that child on the shared line, but does not enter the height the row asks for.
This is a particular case of alignBy, alignBy(FirstBaseline), and a form of align that stands in the same place on the modifier chain, so of the two the last one declared places the child, and either stands in for the row's verticalAlignment.
A child without a FirstBaseline sits against the row's top edge and takes no part in the shared line, the way javax.swing.GroupLayout places a component whose getBaseline gives -1 in a baseline group.
Return
this modifier with the child's placement on the shared baseline declared on it.