Notes to Self

GIMP doesn't do a good job in their File | Open department. But in fairness, the solution is just a search away. If you are a Linux guru it shouldn't be a problem (sadly I am not, so I have to search).

I have to via the interface do a Places | Connect to Server ...
pick Windows share under Service type
type in the ip address of the Windows PC
then able to see MYPICTURES as share (the folder is My Pictures)
your Windows Box will appear on the desktop. But GIMP can't access that.

After that then I can issue the below command, but only on the 2nd time that it wouldn't complain. Is it a bug, maybe, maybe not as I really don't have a solid grasp of what's happening.

1st time failed
mybox@mybox-desktop:~$ sudo smbmount //PC/MYPICTURES /mnt/winshare -o username=yourusername,password=yourpassword
Packet send failed to 169.254.255.255(137) ERRNO=Operation not permitted

2nd time succeeded
mybox@mybox-desktop:~$ sudo smbmount //PC/MYPICTURES /mnt/winshare -o username=yourusername,password=yourpassword
mybox@mybox-desktop:~$

Even you unmount the Windows PC on the desktop, your shared Windows folder will remain on the Linux (Ubuntu) file system, in my case /mnt/winshare where GIMP can access.