Guaranteed Visibility keeping highlighted marks visible at all times potentially difficult with big datasets out of viewport, occlusion, subpixel size linked highlighting of best corresponding item [demo] [TreeJuxtaposer: Scalable Tree Comparison using Focus+Context with Guaranteed Visibility. Munzner et al. SIGGRAPH 2003. http://www.cs.ubc.ca/~tmm/papers/tj] 35