Issues with regex in Find/Replace operations

A discussion was started today in ProZ ( that has brought to light several issues with regex in Find/Replace Operations that, if I remember correctly, are not new but still present even in Studio 2017.

I thought I'd start a thread here to get the discussion going with people who may be monitoring the SDL Community but not the ProZ Trados forum.

Some of the issues discussed in the ProZ thread include:

- Some segments are skipped during the Find operation for no apparent reason

- Some segments throw an error saying that the "Segment start/end cannot be deleted" when attempting to execute a replacement

- Tags are ignored in the Find/Replace operation 

- [ cannot be used in the Replace field (although including both the opening and closing brackets works); using \[ will naturally result in \[ being inserted in the replacement, instead of the bracket being escaped

- ^ is ignored as a start of segment/string anchor during the Find operation

- Find/Replace stops responding after several of these operations