In weeks course format 'show one week' button has a class (wkone) in topics course format it has no class or id

The weeks course format assigns a class to the <img> tag for the square box allowing only one week to be shown. The class is 'wkone'. The same image in topics format has no class at all. It is sometimes required to be able to style this button - in particular, to remove it completely using css. This is only possible in weeks course format.