I've been using paint.net for years, but have been using it more frequently lately.
I have some feature requests. Apologies if these have already been discussed.
Allow expressions in number fields (in addition to literals). It's very handy, for example, if I want to make a canvas size based off of a grid of, say, 16x16 cells, to be able to enter "8*16" rather than do mental math and type in 96.
Guidelines (like Adobe Illustrator). In Illustrator, you can click in the ruler, and drag a guideline into the image. The guideline overlays the image and is not present in the image data, but is used as a visual guideline for the user to help them align stuff. In Illustrator the tools are sensitive to their existence, and can snap a selected object to a guideline.
Support larger zoom levels than 3200% (arbitrary zoom?) I do a lot of really low-res work. When working on super small images, like 8x8 px or 16x16 px, at maximum zoom the canvas still does not fill my window.
Keyboard shortcut to select sample from image vs layer? When I have a selection made by one of the selection tools, if I Ctrl+C to copy some pixels, it copies from the current layer. I saw in the Settings there's an option to sample the whole image rather than the current layer. I'd like to be able to do either, at will, using a keyboard shortcut. Perhaps Ctrl+Shift+C to sample the image for the copy, or to sample all visible layers in the image within the selection area.
Remember multiple selections. It'd be super handy to not have to re-do selections. If I've spent a lot of time doing an intricate selection, I'd like to be able to save it so I can easily go back and re-use it again later if the need should arise. Automatically add selection paths to a list when a selection is created, and allow the user to choose one by clicking on the list item. (The selection is just the paths that make up the marquee, not the image data contained within it.) Allow the user to remove unwanted selection paths from the list if they want to clean it up.
