I am unable to increase the size of the widget icons on the widget controller. When I open the settings and change the size under appearance, it only increases the spacing between the widgets, not the size of the icons. I am currently using Developer Edition 1.15.
This article seems to be the most related but looks to be how to change the size for an icon on a custom widget within a widget container, not all icons within the container.
Set to small:


Set to large:


Brian