steps to reproduce

1. load the zul
2. click the button

current result

no label is displayed

expected result

a label "this is my test" shows up.

root cause

The root cause is that ZK adds a component (and size it) before setting attributes at the client side. Therefore, When zk calculates the child window's height, the bigDiv is still visible and consumes all available space. So that newly-added window becomes 0 height.

workaround:

• replace the outer window with vlayout.
  Vlayout will resize its child component when its child components are removed or added.
• detach the bigDiv
• set height="100%"
  if there is no other sibling, apply the alternative which is the same as vflex=1
• window2.setRenderdefer(10);
  make bigDiv invisible first