parent of subwindow

I have 2 layuots:
| header |
| main |

and popup window.
When I maximize the window I want it to be opened in “main” but not in whole screen (or dragging only in “main”). is it possible?

Not directly, no. There are a couple of alternatives, neither of them easy;

  1. extend the Window widget and add the functionality yourself. This requires knowledge of GWT and Vaadin client side layouting. This is also the only way to limit dragging of the window.

  2. Use CssTools to measure the size of the components you want to overlay and manually set width, height, and position of the window.