UI: ButtonBundle image woes

[makraiz]

I'm certain this was not the intention, but as a new user playing with the UI, I had a heck of a time getting an image as a button working. I am very new to Bevy, having only used it since a few days after 0.6 launched. This is the first feedback I've ever attempted to provide with regards to Bevy.

Initially, my tests included making a ButtonBundle with only the image field defined and everything else defaulted. This resulted in an invisible button that didn't respond to any interactions. Next, I tried a ButtonBundle with an ImageBundle child. This resulted in the image appearing, but it did not function as a button, as it wasn't responding to clicked/hover interactions. This was unlike buttons with defaulted fields and a child of TextBundle which seemed to work exactly as I had expected.

After that, I decided to try to set some of the Style settings. Giving the ButtonBundle a Size in its Style was essential for getting an image to work as a button, no children nodes were necessary. Without it, the default settings were not giving me a working button. You can actually get the same results of an invisible image button with Val::Auto in the Size, which I assume is the Default.

My thinking was that Val::Auto/Default should default to the size of the image. It was difficult to troubleshoot, considering I had already defined the size of the parent nodes, it did not occur to me that I should size the button itself. In any case, if this isn't intended reasoning for Val::Auto, then perhaps an example could be made in the Button example with an image as the button to avoid confusion for others. It also seems inconsistent that a button with text on it needs a child, while a button with an image on it doesn't.

Is the way I accomplished it the intended usage, or have I stumbled into a bug?