hi there.
I use an alternative filemanager called CubicExplorer.
you can download latest version here which is available as a portable application from their homepage (since I can't post links in new forum posts, just search CubicExplorer under Google).

I've noticed that unlike normal Windows file manager, files dragged and dropped from CubicExplorer into RadiAnt viewer are not loaded.

so I wonder if this is a bug of CubicExplorer or a bug of RadiAnt.

remember I use latest RadiAnt version 1.99.53 64bit while CubicExplorer is a 32bit app.
can it be a 32-64 bit incompatibility?

my O/S is Win8.1 x64

You're right Tommy, you can't drag&drop files from a 32-bit application to the 64-bit RadiAnt DICOM Viewer. There's no quick solution to this problem, so we'll be dealing with it sometime later...

while this is still a problem under Win8.1 x64 I've just noticed that drag and drop from 32-bit apps works in Win7 x64

so the problem is limited to Win8.1

any idea why this issue is limited to Win8.1 x64 only?
as said before I don't see this issue under Win7 x64.
I don't have Win10 x64 to test.

We have to check it, Tommy.

just to tell that this issue is not present in Win10 x64

I don't have anymore that Win8.1 x64 PC to test it, however I consider this ticket fixed for me (all my PCs are now Win7 x64 or Win10 x64 machines).