Unable to edit AX7 element properties (dimmed/grayed out)

Quick tips: In AX2012 and the version before, when you click on an element in the AOT, (assuming the properties window is opened) they're editable right away. But in AX7, if you click on an element in your project, the properties is not editable (grayed out, read only). You'll need to double click to open the element in the editor window, then the properties will be enabled for editing.