Visual that shows comment/note when hover over it

Agree! Sometime there is need to educate report users. Adding a textbook will do, but eat up space.

You can do that now with measures + custom tooltips https://powerbi.microsoft.com/en-us/blog/power-bi-desktop-may-update-feature-summary/

This is absolutely necessary, and would make it so we wouldn't have to add another page to the report (or use up a ton of the report canvas) with notes and source links (such as the second page of the example report at https://powerbi.microsoft.com/en-us/blog/visual-awesomeness-unlocked-pulse-chart/)

It has my vote. The current text box takes up room and you also can't adjust the line height which means two lines of 8 font text still takes up a lot of room. I'd love to be able to just add an icon of an 'i' so that when they hover over it some text pops up that adds extra details. The current size of the canvas is so small to begin with to space is precious.

It would be a great improvement ! And please add the possibility to include Web links and file links inside the note

You can create a measure to return a data or string value, for example: = FIRSTNONBLANK([],TRUE) (to use FIRSTNONBLANK in DirectQuery mode, you'll need to enable the PowerBI global option to "Allow unrestricted measures in DirectQuery mode") Add the new measure to your tooltip.