How do I dock a resizable ExtJS Ext.Panel within another resizable docked panel

Question

I have a Modern ExtJS Ext.Panel docked left with resizable set with edge 'east'. IN this left panel, I want

• Flex upper panel
• docked bottom panel with edge 'north' within the docked left panel.

The "flex" upper left panel does not flex. See Sencha fiddle

Answer 1

Just turned out that the docked left panel needed a layout: 'vbox'.