the property editor disappears for a moment

When the layout name is changed, the property editor disappears for a moment.

steps to reproduce the issue:

This occurs in Qt Creator on any platform. It does not occur in Qt Designer.
Here are the reproduction steps:

• Start form editing with QWidget as the form
• Place a QPushButton
• Click on an empty area of the form
• Apply a vertical layout
• Click on an empty area of the form again
• Scroll down the property editor to the very bottom
• Edit the value of layoutName