Resizing (vertical) margin with mouse resizes opposite margin (inverted y-axis)

Summary:

Resizing the top or bottom margin resizes the opposite margin if y-axis is inverted. Regression from earlier developemnt versions (broke sometime in March, will get a bisection to confirm.)

Steps to reproduce:

• open Inkscape
• Check if y-axis points up (if not, set it to point up)
• Using the page tool, attempt to resize top margin

What happened?

Bottom margin was changed

What should have happened?

Top margin should have been changed

Version info

Inkscape 1.3-alpha (4a5d64106d, 2023-05-10, custom)

    GLib version:     2.76.2
    GTK version:      3.24.37
    glibmm version:   2.66.5
    gtkmm version:    3.24.7
    libxml2 version:  2.10.4
    libxslt version:  1.1.37
    Cairo version:    1.17.8
    Pango version:    1.50.14
    HarfBuzz version: 7.1.0

    OS version:       Fedora Linux 38 (Workstation Edition)