bug fix - dissapearing ruler line.
bug fix - dissapearing ruler line.

igvteam/igv.js,NabaviLab/CNV-Visualizer,NabaviLab/CNV-Visualizer,NabaviLab/CNV-Visualizer,igvteam/igv.js,NabaviLab/CNV-Visualizer,NabaviLab/CNV-Visualizer