What does "Constrain proportions" do?

[Adam]

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"Constrain proportions" should actually constrain proportions

Right now, it is not possible to make a square frame that resizes via parent frame. It always distorts into a rectangle. Even with “constrain proportions” toggle selected, it does not constrain the proportions. To make matters even worse, the toggle only “works” when changing the numeric fields of height/width, which then breaks snap-to-pixel-grid. But then when holding shift and dragging a corner of the frame, it constrains proportions and maintains the snap-to-pixel grid functionality. I bel…