We need persistent strip-specific marking, annotations. In backbone assignmers you want a line
on each strip to show where the match position is. These should NOT be shared with other strips the way marks are. The same facility should be usable for annotations generally. We can model it like rulers, or we can keep it in the graphics (posibly stored in the new myultitype attribute), but they must persist, be settable, and deletable at the macro level. Preferably they should have colour, style, thickness, and be either 2D (shown on XY display regardles of Z axis setting) or ND (shown only when within the visible Z slab. They should also ahve an asociated text label that is displayed alongside.
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