(4.11.4 from suse packages actually). for a long time, if i opened an image from the file manager, then hit 'esc', gwenview would close. in more recent versions, it opens image browsing mode instead. 'esc' should be context aware - if i opened an image from the browser, it should return to the browser. if i opened image directly from an external program, 'esc' should close gwenview.
Going to Browse mode when pressing Esc is what most people expect, so it makes sense to have this as a default. Making this context aware as is being proposed here also opens up potential for confusion, because not every user might expect this silent change in behaviour. Lastly, we don't want to add a configuration option for this either. Note that since Bug 385242 was fixed, you could bind Esc to quit to get the old behaviour back (you would still be able to use Enter to switch to Browse mode). Therefore I'm closing this bug.