#912 – Expanding an Expander Will Trigger Layout

When you expand an Expander control, you retrigger a layout operation.  The parent control then lays out the new Expander control, using the expanded portion.

In the example below, we put two Expander controls in a vertical StackPanel.  When we expand the first one, the StackPanel lays out its child controls again, such that the second Expander shifts down below the first.