Desktop test classes each kept identical PumpUntil, Show, Mouse, All,
PressKey, Raise, SetBackingField and Field helpers. They now import
FormTesting and TestReflection; the two Field variants that read a base
type's field or unwrap DrawingLibraryForm keep a one-line wrapper.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
