Popup text appears much smaller than other UI text (on Mac)

[dgholz]

This might be related to #723, but looks like a different issue to me.

Material Maker version:
1.4a3, from bc702ff

OS/device including version:
MacBook Air M1, MacOS Sonoma 15.3.1

Issue description:
The text in popup windows, like preferences, is much smaller than other text.

Steps to reproduce:
Go to Edit menu, click Preferences. Or in the Preview3D panel (or set background to 3D), go to the Model menu & click Configure.

[dgholz]

The exit popup looks fine!

[Calinou]

This is likely a case of Window.content_scale_factor not being applied to Window instances created by Material Maker for its popups.