Delay Showing the ruler, config dialog appear correctly

Fix config dialog show when in custom mode.

When the panel configuration is "custom", the ruler appears at config window creation. However, it should not appear before the dialog component is done, ie before the actual configuration window appears.

In that case it would get focus too soon and then lose it, hiding itself and the main dialog, forcing the user to then click again on the panel toolbox handle to actually show the window