Setting resolution is inconsistent across platforms

On Windows and CUPS and PDF you can set any resolution you like, even negative numbers but on Mac you can only set a value in the supportedResolutions() list.

The Mac supportedResolutions() seems to only return a single value based on whether it is ScreenResolution or HighResolution, regardless of what the printer has support for, but setResolution() has code to find the closest supported resolution from the list to the user requested resolution.

The Windows supportedResolutions() does return a list from the printer, but doesn't check this when setResolution() is called.

The CUPS/PDF supportedResolutions() only ever returns 72, but PDF HighResolution supports 1200, and setResolution() doesn't check against either.

Is there any value in allowing users to set any arbitrary resolution? Surely we can get all 3 platforms to work the same:

• supportedResolutions() returns the list of resolutions taking printer and mode into account
• set Resolution() rejects negative values, and for positive values uses the closest supported resolution