You can try something like this:
In Click Event:

thisform.Tag = 'popup'
DO FORM show_image
thisform.Tag = ''

and in LostFocus

IF thisform.Tag == 'popup'
NODEFAULT
RETURN
ENDIF


It does not work.

a) VFP execute all Click Code, and after start the activation sequence
( Tag is '' in Lostfocus)

b) If you set another flag, and into Lostfocus execute NODEFAULT,
VFP have a bug:

it stop the THISFORM deactivate procedure,
but it do the activate procedure into the other show_image