Thank you for reporting this bug. We will make it our priority to review this report.
Sencha Architect Design View goes blind when...
I added a Ext.tab.Panel to a root of 'Views' in (Project Inspector) to do some design over it, but when I change the property header to true (default appear to be false in the Config property area), when I change the value... the Design View just disappear and no matter that I select another view object, it can't show any of them.
To pass over this problem I have to close Sencha Architect and then start it once again.
if someone else have been reported this... and probably you consider this as repetitive, I'm new here so Im learning how to search here.
I can confirm that Ext 4.1.x has a header configuration in the docs and when setting it to true is throwing an error.
Ext 4.0.x does not expose a header configuration.
We'll investigate it. THanks for the report.