Unity Editor Font Size Changer -- EditorStyles

README.md

Unity Editor font size editor for the editor styles and skins

Change the variable RESIZE_ON_LAUNCH to true or false. Enable resize on launch to set a default font size , using this option will disable the ability to have the window accessible from the context menu ( Window > Editor Font Size ) - because this is a hacky way to enforce default global font size on application launch ( on script assembly reload and on application enter / exit play mode )

Preview	Added custom styles ( 600+ )	Added Global Zoom ( increment all styles in the same time )

GIF PREVIEW : https://imgur.com/8jsy8sN

EditorFontSize.cs

#if UNITY_EDITOR

using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System.Reflection;

public class EditorFontSize : EditorWindow
{
    // enable resize on launch to set a default font size , using this option will disable the ability to have the window accassible 
    // from the context menu ( Window > Editor Font Size ) - bc this is a hacky way to enforce default global font size on application 
    // launch , on script assembly reload and on application enter / exit play mode 

    public static bool RESIZE_ON_LAUNCH = true;
    public static int DEFAULT_GLOBAL_FONT_SIZE = 14;

    [InitializeOnLoadMethod] static void DefaultSize()
    {
        if( ! RESIZE_ON_LAUNCH || DEFAULT_GLOBAL_FONT_SIZE <= 10 ) return;
        var w = GetWindow<EditorFontSize>();
        w.GUICallback = () => {
            w.Resize( DEFAULT_GLOBAL_FONT_SIZE - 10 ) ;
            w.Close();
        };
    }

    [MenuItem("Window/Editor Font Size")]
    static void Open()
    {
        if( RESIZE_ON_LAUNCH ) return;

        GetWindow<EditorFontSize>("Editor Font Size").minSize = new Vector2(180, 30);
    }

    Dictionary<string, bool> foldouts;

    bool Header(string s)
    {
        if (foldouts == null) foldouts = new Dictionary<string, bool>();
        if (!foldouts.ContainsKey(s)) foldouts.Add(s, true);
        GUILayout.Space(5);
        var foldout = EditorGUILayout.Foldout(!foldouts[s], s, true);
        foldouts[s] = !foldout;
        return foldout;
    }

    private void OnDisable()
    {
        guiSkins = null;
        editorStyles = null;
        propFontSizevalidity?.Clear();
        propFontSizevalidity = null;
    }

    static List<GUIStyle> styles;

    PropertyInfo[] editorStyles;
    PropertyInfo[] guiSkins;

    void GrabProperties()
    {
        if (editorStyles == null || editorStyles.Length < 1)
        {
            var flags = BindingFlags.Static | BindingFlags.Public | BindingFlags.GetProperty;
            editorStyles = typeof(EditorStyles).GetProperties(flags);
        }
        if (guiSkins == null || guiSkins.Length < 1)
        {
            guiSkins = GUI.skin.GetType().GetProperties();
        }
    }

    Vector2 scroll;

    System.Action GUICallback;

    private void OnGUI()
    {
        rowCount = -1;

        GrabProperties();

        InitStyles();

        var delta = FontSizeRow("Global Zoom", EditorStyles.miniLabel.fontSize.ToString());
        if (delta != 0 && EditorStyles.miniLabel.fontSize + delta > 0)
        {
            Resize( delta );
        }   

        GUILayout.Label("", GUI.skin.horizontalSlider);

        using (var scope = new GUILayout.ScrollViewScope(scroll))
        {
            scroll = scope.scrollPosition;

            if (Header("Editor Styles"))
                foreach (var x in editorStyles)
                    ModifyProp(x, null);

            if (Header("GUI skins"))
                foreach (var x in guiSkins)
                    ModifyProp(x, GUI.skin);

            if (Header("Custom Styles"))
                foreach (var x in GUI.skin.customStyles)
                {
                    FontSizeRow(x);
                    RepaintAll();
                }
        }

        if( GUICallback != null ) GUICallback.Invoke();
    }

    void Resize( int delta )
    {
        // Keep watch for duplicates ( Prevent double modifications )
        styles = new List<GUIStyle>();

        foreach (var x in editorStyles)
        {
            if (!ValidFontProp(x, null)) continue;
            var s = (GUIStyle)x.GetValue(null, null);
            if (styles.Contains(s)) continue;
            styles.Add(s);
            s.fontSize += delta;
        }

        foreach (var x in guiSkins)
        {
            if (!ValidFontProp(x, GUI.skin)) continue;
            var s = (GUIStyle)x.GetValue(GUI.skin, null);
            if (styles.Contains(s)) continue;
            styles.Add(s);
            s.fontSize += delta;
        }
        foreach (var x in GUI.skin.customStyles)
        {
            if (!ValidFontStyle(x) || styles.Contains(x)) continue;
            FixZeroSize(x);
            styles.Add(x);
            x.fontSize += delta;
        }

        styles.Clear();

        RepaintAll();
    }

    void RepaintAll() { foreach (var w in Resources.FindObjectsOfTypeAll<EditorWindow>()) w.Repaint(); }

    Dictionary<PropertyInfo, bool> propFontSizevalidity;

    bool ValidFontProp(PropertyInfo x, object item)
    {
        if (propFontSizevalidity == null) propFontSizevalidity = new Dictionary<PropertyInfo, bool>();
        if (propFontSizevalidity.ContainsKey(x)) return propFontSizevalidity[x];

        propFontSizevalidity.Add(x, true);

        if (string.IsNullOrEmpty(x.Name)) propFontSizevalidity[x] = false;
        else if (x.PropertyType != typeof(GUIStyle)) propFontSizevalidity[x] = false;
        else if (x.GetValue(item, null) == null) propFontSizevalidity[x] = false;
        else if (((GUIStyle)x.GetValue(item, null)).fontSize < 1) propFontSizevalidity[x] = false;

        return propFontSizevalidity[x];
    }

    void ModifyProp(PropertyInfo x, object item)
    {
        if (!ValidFontProp(x, item)) return;

        var style = ((GUIStyle)x.GetValue(item, null));
        var val = style.fontSize;
        int ret = FontSizeRow(x.Name, val.ToString());
        if (ret == 0 || val + ret <= 0) return;
        style.fontSize = val + ret;
        RepaintAll();
    }

    GUIStyle evenBG;
    GUIStyle oddBG;

    void InitStyles()
    {
        if (evenBG != null) return;
        GUIStyle s = "CN EntryBackEven";
        evenBG = new GUIStyle(s);
        s = "CN EntryBackodd";
        oddBG = new GUIStyle(s);
        evenBG.contentOffset = oddBG.contentOffset = new Vector2();
        evenBG.clipping = oddBG.clipping = TextClipping.Clip;
        evenBG.margin = oddBG.margin =
        evenBG.padding = oddBG.padding = new RectOffset();
    }

    int rowCount = 0;

    void FixZeroSize(GUIStyle s) => s.fontSize = s.fontSize < 1 ? 11 : s.fontSize;

    bool ValidFontStyle(GUIStyle s) => !(s == null || string.IsNullOrEmpty(s.name));

    void FontSizeRow(GUIStyle s)
    {
        if (!ValidFontStyle(s)) return;

        FixZeroSize(s);

        var x = FontSizeRow(s.name, s.fontSize.ToString());

        if (x != 0 && x + s.fontSize > 0) s.fontSize += x;
    }

    int FontSizeRow(string name, string size)
    {
        if (string.IsNullOrEmpty(name) || size == "0") return 0;

        rowCount++;

        var width = GUILayout.MaxWidth(Screen.width);

        using (new GUILayout.HorizontalScope(rowCount % 2 == 0 ? evenBG : oddBG, width))
        {
            GUILayout.Label(name);
            GUILayout.FlexibleSpace();

            if (GUILayout.Button("-", EditorStyles.miniButtonLeft)) return -1;

            using (new EditorGUI.DisabledGroupScope(true))
                GUILayout.Label(size, EditorStyles.miniButtonMid, GUILayout.Width(30));

            if (GUILayout.Button("+", EditorStyles.miniButtonRight)) return +1;

        }

        return 0;
    }
}

#endif

This is still an issue with Ubuntu 24.04 and the 6.2 beta. The script kind of works, but line spacing are messed up and not all windows have the font with the correct size.
The GDK environment variables either don't work or they do and the text is just enormous. GDK_SCALE does not work with partial scaling.
However I installed Unity 6 on Ubuntu 22.04 and it just worked, no hacks.