setting minimum leader glyph size


I am using SetMaximumLeaderGlyphSize for a caption widget arrow to make sure the arrow head does not become too large when zooming out. However, the arrow head becomes very tiny when zooming in. There seems to be no “SetMinimumLeaderGlyphSize” to ensure that the arrow head is always visible. Is there some other way to accomplish this? Is it possible to obtain the length of the leader and to dynamically set the glyph size?