on both 18.04 with a Dolphin 17.something and Neon-testing with a Dolphin 20.something ,,,I can turn off "tool tips" in Dolphin>settings>configure dolphin>general>show tool tips , AND with it off I do NOT get the "preview window" like in your post #19 BUT do get the "tool tip" (on the tool bar) like in your post #14.
turning ON that "tool tip" in Dolphins settings only affects the pop up preview on mouse over of files (like in your post #19)

maybe their is some quirk in the dolphin 19-seres that is doing this to you ??
VINNY


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