Repeat dock/undock change the original size

[tlaemmlein]

System: Windows 10 / VS 2019
kddockwidgets version: 1.6.0 with bug fix: #96

Steps:

• Configure a dock layout of widget like the following animation
• Dock and dock a widget in the lower left corner and repeat this
• Observe that the original size won't be restored and the widget's 2 and 5 are getting smaller
  

I expect that after the widget is undock the size will be restored.