In the docs for Ext.form.Panel, the definition for the config value "height" reads:

height : Number/String
The height of this Component; must be a valid CSS length value, e.g: 300, 100px, 30%, etc. By default, if this is not explicitly set, this Component's element will simply have its own natual size.
What I'm finding, however, is that if the height of the panel is not explicitly set it will collapse to nothing, or to a thin black line, and none of the content inside the panel will be visible.

If I were to not need a form's functionality I could just use Ext.Panel, which does behave as per the height definition above.

Is this a bug? Am I missing something?