a new TLA+ Toolbox 1.5.2 release has been made available . This release fixes several bugs, contains performance improvements and minor features. See the changelog  (updated soon) for a high-level description of changes or check the list of all commits .
Any previous Toolbox will automatically ask to update to 1.5.2 upon the next Toolbox startup.
*Mac users beware*: Please do not use the Toolbox's built-in update mechanism this time! Starting with this new version, the Toolbox is released as an application bundle which better fits the Mac user experience. To install the new Toolbox, simply extract the Toolbox download to your “/Applications/” folder. Moving the directory named “workspace” from the old Toolbox installation located in “.../toolbox/toolbox.app/Contents/MacOS/” to the /Applications/TLA+ Toolbox.app/Contents/MacOS folder prior to launching, makes sure that the Toolbox remembers your specs.