Draw informations in 3D_view

Question

I'm trying to script a baking in network and it works but now I'd like to print informations for the user (clients whose are connected for example)

I tried to print those informations in the 3D_view but it doesn't work because of the "context"

Code:

import bpy
import time
import blf
import bgl
from threading import Thread

class OperatorMaster(bpy.types.Operator):
    bl_description = "Use this computer as master for baking"
    bl_idname = "baking.master"
    bl_label = "Operator Master"

    def execute(self, context):

        threadCatchClients = Thread(target = catchClients, args = [context]) #Create a thread for function catchClients
        threadCatchClients.start()

        [...] #Rest of code

def catchClients(context):

    h = context.region.height

    [...] #Some code

    # Draw
    if len(clients) != 0:
        pos_y = h - 50
        bgl.glColor4f(0.0, 1.0, 0.0, 0.7)
        for c in clients:
        # Draw text in this region.
        pos_x = 20
        pos_y -= 20
        _handle = bpy.types.SpaceView3D.draw_handler_add(drawInformations, (c, pos_x, pos_y), 'WINDOW', 'POST_PIXEL')
        context.area.tag_redraw()

    else:
        pos_x = 20
        pos_y = h - 50
        bgl.glColor4f(0.0, 1.0, 0.0, 0.7)
        _handle = bpy.types.SpaceView3D.draw_handler_add(drawInformations, ('No clients for the moment', pos_x, pos_y), 'WINDOW', 'POST_PIXEL')
        context.area.tag_redraw()

   time.sleep(1)
   while True:

        [...] #Some code

        if masterClosed:
            break

        else:
            # Draw
            if len(clients) != 0:
                pos_y = h - 50
                bgl.glColor4f(0.0, 1.0, 0.0, 0.7)
                for c in clients:
                    # Draw text in this region.
                    pos_x = 20
                   pos_y -= 20
                    _handle = bpy.types.SpaceView3D.draw_handler_add(drawInformations, (c, pos_x, pos_y), 'WINDOW', 'POST_PIXEL')
                    context.area.tag_redraw()

            else:
                pos_x = 20
                pos_y = h - 50
                bgl.glColor4f(0.0, 1.0, 0.0, 0.7)
                _handle = bpy.types.SpaceView3D.draw_handler_add(drawInformations, ('No clients for the moment', pos_x, pos_y), 'WINDOW', 'POST_PIXEL')
                context.area.tag_redraw()

        time.sleep(1)

And I have a ERROR:

    Exception in thread Thread-1:
Traceback (most recent call last):
  File "C:\Program Files\Blender Foundation\Blender\2.79\python\lib\threading.py", line 914, in _bootstrap_inner
    self.run()
  File "C:\Program Files\Blender Foundation\Blender\2.79\python\lib\threading.py", line 862, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\Admin\AppData\Roaming\Blender Foundation\Blender\2.79\scripts\addons\AxeonBakingTool\buttons.py", line 223, in catchClients
    h = context.region.height
AttributeError: 'NoneType' object has no attribute 'height'

Is there someone who can help me?

Thanks a lot.