I like using the Images toolbar to convert and resize thumbnails of pictures as it is quicker than right clicking the image to use the option from the context menu. What I notice is that when there are no images in the folder, some of the options and icons auto-hide from the toolbar, which is logical I suppose, as why would you want to use the Thumbnail size slider with no images present?! But I would like it to be present all the time as I want to constantly see how much space on the toolbar I have left as I cramp my toolbars with lots of icons and options I use regularly. When some icons auto-hide, it makes it difficult to tell where they were before and therfore you cannot add more without pushing the others out.
There's no way to prevent them from hiding at the moment.
Future feature, perhaps?