Jumping back into some GUI work and running across several issues, figured might as well drop them all in one, if that is alright. Attached GIFs for a few of them, to make it better explained.
>Clicking eyedropper on area to get color, also performs actual click, losing selection

>Using middle-click to pan, if a GUI item is selected, when the middle-click is released it counts as a left click and selection is lost

>Holding "CTRL" or "SHIFT" to select multiple items often does not work, unless zoomed in fairly close, the click only selects the object and does not add to selection

>With multiple objects selected (simple sprites, in my case), "Right-Click > Attach" menu is relative only to last-selected object

>With multiple objects selected, keyboard shortcuts only affect last selected object (ie, Alt-Shift-C to add box collider)
>With multiple objects selected, clicking on the Unity frame loses selection