Currently the way Transform works in Pixelmator Pro is a bit counter intuitive.
Most of the time I do not need to have the proportions constrained by default when I transform an object.
Unchecking the checkbox every time does get in the way.
Please consider providing a global setting for users –like me– that wish to have the Constrain Proportions option disabled by default.
Also pressing the SHIFT key when transforming an object does keeps the aspect ratio, so I don't quite see why this is turned on by default.
Thanks.