Canvas jumping when font size is increased in theme preferences

Summary:

When the font scaling is set to > 100%, the canvas jumps when an object is selected / deselected, because the N/A text in the status bar is larger than the color indicator rectangles (kudos to @karliss for figuring this out here: #4760 (comment 1766689784) ).

Steps to reproduce:

• open Inkscape
• Edit > Preferences > Interface > Themeing : Font scale : e.g. 120%
• draw object
• select it
• deselect it

What happened?

Canvas jumps.

What should have happened?

No jumping.

This happens coz different toolbars have incosisten styling we should investigate and unified how it is styled (xml+css)

I'd suggest replacing the N/A text by some kind of graphic, e.g. a thin horizontal line, like a '-' (but not a dash, as probably the line-height is reserved).

Version info

    Inkscape 1.4-dev (07fdc5641e, 2024-03-10)

                      Compile  (Run)
    GLib version:     2.72.4
    GTK version:      3.24.33 (3.24.33)
    glibmm version:   2.66.2
    gtkmm version:    3.24.5
    libxml2 version:  2.9.13
    libxslt version:  1.1.34
    Cairo version:    1.16.0 (1.16.0)
    Pango version:    1.50.6 (1.50.6)
    HarfBuzz version: 2.7.4 (2.7.4)

    OS version:       Linux Mint 21.3