Dynamic height widget ?

Hello.
How can i create a widget that fills window by height ?
There's _dynamic layout functions, but they are only for width, not height.

The issue does not name a file, test, or entry point. Start by locating the dynamic layout functions referenced in the issue and determine how widget height is currently calculated; done would mean documenting or implementing a clear way for a widget to fill the window height.

Written by the indexing model from the issue text.