If you use Agile Requirements Designer (ARD) 2.5.5 or older, you may feel inconvenient regarding opening VTF file.
When open VTF file directly (through Windows Explorer, shortcut on desktop and so on), AgileDesigner always open as new instance. Additionally, license is used for each instances.
Release: TCDWRK99000-2.5-Agile Requirements Designer-Workgroup
ARD 2.6 has new feature.
If AgileDesigner is already opened, new tab will be opened instead of new instance when open VTF file with double clicking.
Additionally, you can drag and drop VTF file onto AgileDesigner. And then, you can see the flow as new tab.
Please refer to other enhancements in ARD 2.6: