Has anyone experienced the problem of TS (with Citrix) not detecting double-clicks properly from a VFP app ?

I have a Listbox with code in the DblClick Event to select the item (ie act as CmdOk.Click()).
Works fine on a local FAT PC - but not when loaded onto TS. When I double-click (at whatever speed) then I get an hour glass come up app just seems to hang. Clicking elsewhere removes the hourglass and I'm back as though no clicks been done. If I triple click the correct action is taken !
My first thought was that it was a configuration problem with TS or Citrix whereby not all mouse clicks are being picked up correctly. However- my colleague who has setup TS/Citrix has tried several different options and none seem to make a difference.
I get the same problem when double-clicking in a grid row.

However, when run Word and double-click on an AutoText entry this works fine - so seems to be a VFP-specific problem.

Any suggestions/advice gratefully received.