The main improvements of Solarus 1.3 are in the quest editor: there is now a sprite editor, the quest tree gives more control over various files, and tile patterns are now identified by strings. There are also a few changes, like more customizable switches and bugfixes. Good news: there is no incompatible change in the Lua API. The only changes in the Lua API are bugfixes and new features, in particular with sprites and switches.
As always, you should make a backup before any upgrade.
In this page, we only focus on the incompatibilities. See the changelog to know more about the new features.
Data files other than scripts can be upgraded automatically with the editor.
Open your quest with Solarus Quest Editor 1.3 and a dialog will let you to perform the upgrade.
Note that the operation can also be done from the command line, by running the script update_quest.lua in the tools directory of the git repository. Internally, the editor actually calls this script.
The only changes in the data files are minor:
The Lua scripting API of Solarus 1.3 introduces new functions, in particular on sprites and switches, but there is no incompatibility. Scripts that worked with Solarus 1.2 also work with Solarus 1.3. So you have nothing to do.