I'm still having this problem of the Export dialogue box that disappears behind the CafeTran UI :(.
To be able to confirm on my Mac, the issue needs to be reproduced. Here, the Export dialog appears in front right after clicking the Export button.
Normally, the last steps that I execute before exporting, is running a bunch of QA checks. Perhaps that has something to do with it (with regards to losing focus or so).
Perhaps it's relevant: this hiding of the Export dialogue box happens when I click on the Export button above the project segments table.
I start CafeTran, I click the button Export, the dialogue box disappears. No other app switching involved.
It looks like the Export button is the culprit: when I choose Export all documents from the Project menu, the Export dialogue box doesn't disappear.
Confirmed and fixed in the coming build.