Hello!
I’ve “developed” a script to change background color depending on what mode I’m working with. I.E: gray when object mode, red-ish when edit mode… I don’t what to move eyes to know what mode I’m currently working… you know 
It’s a very primitive script, and I do know it’s causing some caos with other add-ons, but it’s my script and I like it.
Since sharing is caring, and I do know this board is full of people talented with these endeavours, I´d like to sharing it here to hear some suggestions and mods, and, why not, lets put this elsewhere to a broad audience if someone wants to give it a try, or just make its own… whatever! This script is serving me well since 2.80, and I found it a vital part of my daily work. I only want this bloody thing works better! (i.e. have a proper color picker at preferences) DISCLAIMER: I’ve almost ZERO idea on python coding. I do know the basics of programming, but nothing more, right? don’t roast me 
bl_info = {
"name": "Active Background",
"author": "Dspazio",
"version": (1, 0),
"blender": (2, 80, 0),
"location": "View3D",
"description": "Changes background gradient color for each mode.",
"warning": "",
"doc_url": "",
"category": "Themes",
}
import bpy
from bpy.app.handlers import persistent
Modes = {'OBJECT':(0.30, 0.30, 0.30),
'EDIT':(0.30, 0.20, 0.20),
'SCULPT':(0.05, 0.05, 0.05),
'VERTEX_PAINT':(0.05, 0.05, 0.05),
'WEIGHT_PAINT':(0.05, 0.05, 0.05),
'TEXTURE_PAINT':(0.05, 0.05, 0.05)}
@persistent
def my_handler(scene):
mode = bpy.context.object.mode
bpy.context.preferences.themes[0].view_3d.space.gradients.high_gradient = Modes[mode]
class addActiveBackgroundPreferences(bpy.types.AddonPreferences):
bl_idname = __name__
edit_mode_color: bpy.props.FloatVectorProperty(name="Edit Mode Color", subtype='COLOR', default=Modes['EDIT'], size=3, min=0, max=1)
def draw(self, context):
layout = self.layout
layout.label(text='Edit Mode :')
row = layout.row()
row.prop(self, 'edit_mode_color', expand=True)
def register():
bpy.app.handlers.depsgraph_update_post.append(my_handler)
bpy.utils.register_class(addActiveBackgroundPreferences)
def unregister():
bpy.app.handlers.depsgraph_update_post.remove(my_handler)
bpy.utils.register_class(addActiveBackgroundPreferences)
if __name__ == "__main__":
register()
Cheers!