Visor & drag'n'drop

When dragging a file, if one wants to invoke the visor, most double taps KB shortcuts won’t work (only shift + shift will open the visor).
The normal KB shortcut (the one you have to record) seems OK (I didn’t try many different values though).
Also, it would be great if Visor would open when dragging something on the Finder dock icon, if no Finder window are opened.