FLTK 1.3.7 is a maintenance release for macOS only. It fixes one regression introduced in FLTK 1.3.6 and two long standing timer issues on macOS.
Other platforms than macOS are not affected.
We recommend all macOS users to upgrade to FLTK 1.3.7.
This release does not contain new "ABI features". The ABI (Application Binary Interface) is 100% compatible with releases 1.3.5 and 1.3.6.
The new release 1.3.7 (source and documentation) can be downloaded here: https://www.fltk.org/software.php
macOS: Fix a timer inconsistency and prevent a crash macOS: Fl::add_timeout() must always create a new timer (#248) macOS: Avoid premature FL_RELEASE event at start of drag-n-drop operation.
For more information on previous releases see CHANGES in the root directory of the source distribution or directly in our FLTK source repository on GitHub:
CHANGES (as of Release 1.3.7)