I have problem....
I search this site but no found a post with solution...
When i move mouse over graphics file, i don't show picture preview.
How to fix it?
Well you didn't look too hard... 
Try reading this faq: [How to add Thumbnails to InfoTips)
Thanks, Steve, this is it.
Why InfoTips cleared itself?
Had you turned off the Images file type group?
You asking for this?
Nope, file types group (menu settings/file types)... not folder format...
And now?
What do you want to know ?
Your problem is not solved ?
Yes, is solved - but i want to know why this is erased?
Maybe your config comes from a time before Opus had anything in those infotips by default.
Whatever the reason you can add the default Images infotip using the Samples drop-down list/button at the bottom of the InfoTip definition tab.
is possible to define size of the thumbnail what is displayed on this infotips?
Yes, Preferences/Lister Display Modes - Thumbnails Modeand change thumbnail size...
Yes - but there any way to leave this as is and set only for "over mouse" in infotips?
I don't want to resize my standard thumbnail to view picture when i move mouse over pic and set it again to standard resolution in prefereneces when i want to go thumbnail mode...
nope
it's sad 
Dear leo - another innovation to put into Dopus...
I think you are mistaking me for the people who write Opus.
Yes, you correct - but you write so many post... i thought you are in opus team...