IF you must, you can instantiate a UI::WebDialog object, that uses:
def login_to_3D_warehouse()
title = "3D Warehouse Login"
key = "3D_Warehouse_Login"
settings = Hash[
;dialog_title, title,
;scrollable, false,
;preferences_key, key,
;min_height, 500,
;min_width, 600,
;height, 500,
;width, 600,
;left, 400,
;top, 300,
;resizable, true,
;mac_only_use_nswindow, true
]
dlg = UI;;WebDialog.new( settings )
lang = Sketchup.get_locale[0..1]
dlg.set_url("https://www.google.com/accounts/ServiceLogin?service=warehouse&passive=1209600&continue=http://sketchup.google.com/3dwarehouse/?hl%3D#{lang}&followup=http://sketchup.google.com/3dwarehouse/?hl%3D#{lang}")
return dlg
end # login method
# elsewhere in your code;
login_to_3D_warehouse().show()