Searching for empty translations in OmegaT

OmegaT searches are very powerful. One feature OmegaT does not have (yet?) is the ability to register common searches for later use.
There are at least 2 RFEs for that on the OmegaT development site, one registered in 2006 (by me) and one in 2014.

In the meanwhile, there are at least 2 searches that you want to remember:

1. searches for non translated segments
2. searches for segments that have been set to <EMPTY> (they are translated but the translation being empty, the source won't appear in the target document).

Searches for non translated segments

The logic is straightforward:

You want to search for any one character in source that is untranslated.

In a search, "any one character" can be expressed by the regular expression "." (period). So you put a period in the search field and you make sure you have selected "Regular expressions" below it. That "any one character" is to be found in "source", so you uncheck anything else but "source" in the line below that. Then you specify "Untranslated", since that's exactly what your looking for, and you can eventually select "all matching segments" to make sure non unique segments are all displayed.

The search scope will be "Project" and only "Memory".

Searches for <EMPTY> segments

In OmegaT, when a segment is left untranslated, the source text appears in the target document. An easy way to get around this is to translate the segment with a space. The problem is that sometimes you really want to not use anything in target. For this, OmegaT allows you to "Set [an] empty translation" in the Edit menu. Once you do that, the segment will be empty but translated (it appears in the same color as the other translated segments when you select "Mark translated segments" in the View menu), and OmegaT will display it with the <EMPTY> string when you've left it.

To search for such segments, the logic is a bit different:

You want to search for an empty string in target that is translated.

In a search, "an empty string" can be expressed by the regular expression "^$" (caret, followed by dollar). The ^ stands for the beginning of the line and the $ for its end, with nothing in between the string is empty. So you put a caret followed by a dollar sign in the search field and you make sure you have selected "Regular expressions" below it. That "empty string" is to be found in "target", so you uncheck anything else but "target" in the line below that. Then you specify "Translated", since that's exactly what your looking for, and you can eventually select "all matching segments" to make sure non unique segments are all displayed.

The search scope will be "Project" and only "Memory".