When creating a new widget that derives from an existing widget it will not show up in the palette hierarchy after restarting the editor

When creating a widget based on a widget that is available by default in the editor it will not show up in the palette once the editor has been closed until the widget itself has been opened during that editor session.

1. Download the attached project
2. Open the project
3. Open the widget "Interface"
4. Open "ForgetfulButton"
5. Search the palette for "ForgetfulButton" (it should be in the common section)
6. Close the editor
7. Reopen the editor
8. Open the widget "Interface" (do NOT open "ForgetfulButton" first)
9. Search the palette for "ForgetfulButton"

Result: The widget that was created does not show up in the palette if the editor has been restarted (until the widget has been opened)
Expected: The widget would show up in the palette