FontSwitcher.cs

#if UNITY_EDITOR
using System.Reflection;
using UnityEngine;
using UnityEditor;

public class FontSwitcher : EditorWindow
{
	[MenuItem("Font/Show Window")]
	public static void ShowFontWindow()
	{
		GetWindow<FontSwitcher>();
	}

	public void OnGUI ()
	{
		EditorGUI.BeginChangeCheck();
		string newFontName = EditorGUILayout.DelayedTextField("Unity Font", GUI.skin.font.fontNames[0]);
		if (EditorGUI.EndChangeCheck())
		{
			ReplaceFont((Font)EditorGUIUtility.LoadRequired("Fonts/Lucida Grande.ttf"), newFontName);
			ReplaceFont((Font)EditorGUIUtility.LoadRequired("Fonts/Lucida Grande Bold.ttf"), newFontName);
			ReplaceFont((Font)EditorGUIUtility.LoadRequired("Fonts/Lucida Grande Small.ttf"), newFontName);
			ReplaceFont((Font)EditorGUIUtility.LoadRequired("Fonts/Lucida Grande Small Bold.ttf"), newFontName);
			ReplaceFont((Font)EditorGUIUtility.LoadRequired("Fonts/Lucida Grande Big.ttf"), newFontName);
			// replace also skin's font name - the change _sems_ to be ignored/inconsistent with UI otherwise
			ReplaceFont(GUI.skin.font, newFontName);
			
			typeof(EditorApplication).GetMethod("RequestRepaintAllViews", BindingFlags.Static | BindingFlags.NonPublic).Invoke(null, null);
			// after all the above the change seems to be still ignored - manual Reimport of some (any) asset in the project seems to work though
			// instead of reimporting some asset, reimport 'Assets/Editor' folder asset (w/o its content..); 'Assets/Editor' porbably exists since we're running in Editor script
			// TODO: don't hardcode 'Assets/Editor'
			AssetDatabase.ImportAsset("Assets/Editor", ImportAssetOptions.ForceUpdate);			
		}
	}

	private void ReplaceFont(Font font, string fontName)
	{
		if (font.name.Contains("Bold"))
			font.fontNames = new string[] { fontName + " Bold" };
		else
			font.fontNames = new string[] { fontName };
		font.hideFlags = HideFlags.HideAndDontSave;
	}
}
#endif