I discovered this bug when debugging my app on Windows Phone Nokia Lumia 820.

I use Ext.Msg.Alert() to pop up a dialog in which contains some error messages.

The button on the dialog cannot be clicked.


Then I use weinre to remove many UI components one by one.

After the map and its container were removed, the Okay button in the dialog was finally clickable.


So that's why I come to this conclusion: the MessageBox generated by Ext.Msg.alert() isn't displayed on the most top layer.