Created attachment 110122 [details]
Example of current Dialog generated by Dolphin

When a file named "X" is moved into a folder that already contains a file named "X", dolphin pops up a dialog notifying the user that "this action will overwrite the destination". The dialog indicates the size of the source and target.

Unfortunately, the size may not carry enough information for the user to make an informed decision. In particular, the size of the two files may be identical, and the files may still differ. The "Modify Date", although shown, may be confusing or wrong.

Improvement: Help the user out by indicating that the MD5 sum of left and right files match (evidently, if the size doens't match, this does not need to be computed)

MD5 hash is sufficient here because one is not working in a context in which a weak hash is of relevance. One just want a fast hashing algorithm.

For large files computing the MD5 sum may be expensive. Thus, for files above a certain size (which should be configurable), the dialog could offer the option to compute the MD5 sum on demand (by clicking a button) instead of computing it outright.

The "Apply to All" option would continue to not care about MD5 hashsums of the files.