type WindowIcon struct {
// Size is the width and height in pixels. 512 or more keeps it sharp where the
// desktop shows it large.
Size int
// RGBA is Size*Size straight (not premultiplied) 8-bit pixels, top row first.
RGBA []byte
}WindowIcon is the application's square picture, the source of every icon the desktop shows for a running window; see Config.Icon. Supply it as the artist drew it: a full-bleed square, which each platform shapes to its own convention (the macOS tile with its margin, the plain rounded tile elsewhere), or a picture whose corners are transparent, which is only scaled.
StatusIcon#func (icon WindowIcon) StatusIcon(size int) StatusIconStatusIcon is the picture as a status-area icon of size pixels, in the form the platform's status area expects. macOS tints its icons to the menu bar, so there it is the picture's mark alone, a template; Windows and Linux show an icon as it is, so there it is the same rounded tile a window shows.