Control bar icon size isn't applied when opening a new window

Summary:

Control bar size "Preferences > Interface > Toolbars > Control" isn't automatically applied for new windows.

Steps to reproduce:

• open Inkscape
• set control bar scale to 200% (move back and forth if you had it previously), pay attention to how big it looks
• restart Inkscape, notice that the icon size is more like 100%
• preferences > Interface > Toolbars > Control bar icon size
• the setting should still be at 200%, move the slider back and forth returning to 200%
• notice the sudden jump in size
• create new document
• drag the new document tab out as separate window
• notice that the control bar size is small again

What happened?

When a new inkscape window is created control bar size doesn't match the preferences.

What should have happened?

Restarting inkscape or otherwise creating new window should use the chosen control bar icon size.

Sample attachments:

I'll be glad to make a video, if you like. Just let me know.

Version info

Inkscape 1.5-dev (377dbcb, 2025-08-09)

                      Compile  (Run)
    GLib version:     2.80.0
    GTK version:      4.14.5 (4.14.5)
    glibmm version:   2.78.1
    gtkmm version:    4.14.0
    libxml2 version:  2.9.14
    libxslt version:  1.1.39
    Cairo version:    1.18.0 (1.18.0)
    Pango version:    1.52.1 (1.52.1)
    HarfBuzz version: 8.3.0 (8.3.0)
    Poppler version:  24.02.0

    OS version:       Linux Mint 22