Multiple WindowsBaloonTip / TrayTip Notifications?

Question

If you were to use this code below to create TrayTips (BaloonTips) in the Notification Area you will notice that it only allows one message and then gets stuck and errors out.

The code was taken from here:

# -- coding: utf-8 --

from win32api import *
from win32gui import *
import win32con
import sys, os
import struct
import time

class WindowsBalloonTip:
    def __init__(self, title, msg):
        message_map = {
                win32con.WM_DESTROY: self.OnDestroy,
        }
        # Register the Window class.
        wc = WNDCLASS()
        hinst = wc.hInstance = GetModuleHandle(None)
        wc.lpszClassName = "PythonTaskbar"
        wc.lpfnWndProc = message_map # could also specify a wndproc.
        classAtom = RegisterClass(wc)
        # Create the Window.
        style = win32con.WS_OVERLAPPED | win32con.WS_SYSMENU
        self.hwnd = CreateWindow( classAtom, "Taskbar", style, \
                0, 0, win32con.CW_USEDEFAULT, win32con.CW_USEDEFAULT, \
                0, 0, hinst, None)
        UpdateWindow(self.hwnd)
        iconPathName = os.path.abspath(os.path.join( sys.path[0], "balloontip.ico" ))
        icon_flags = win32con.LR_LOADFROMFILE | win32con.LR_DEFAULTSIZE
        try:
           hicon = LoadImage(hinst, iconPathName, \
                    win32con.IMAGE_ICON, 0, 0, icon_flags)
        except:
          hicon = LoadIcon(0, win32con.IDI_APPLICATION)
        flags = NIF_ICON | NIF_MESSAGE | NIF_TIP
        nid = (self.hwnd, 0, flags, win32con.WM_USER+20, hicon, "tooltip")
        Shell_NotifyIcon(NIM_ADD, nid)
        Shell_NotifyIcon(NIM_MODIFY, \
                         (self.hwnd, 0, NIF_INFO, win32con.WM_USER+20,\
                          hicon, "Balloon  tooltip",msg,200,title))
        # self.show_balloon(title, msg)
        time.sleep(10)
        DestroyWindow(self.hwnd)
    def OnDestroy(self, hwnd, msg, wparam, lparam):
        nid = (self.hwnd, 0)
        Shell_NotifyIcon(NIM_DELETE, nid)
        PostQuitMessage(0) # Terminate the app.

def balloon_tip(title, msg):
    w=WindowsBalloonTip(title, msg)

Answer 1

As you can see if you were to try and send multiple balloon_tip's to the WindowsBalloonTip class you will get the following error:

File "C:/WindowsBalloonTip.py", line 20, in __init__
    classAtom = RegisterClass(wc)
error: (1410, 'RegisterClass', 'Class already exists.')

Looking at Microsoft's documentation of the RegisterClass you need to Unregister the class as well by using UnregisterClass(lpClassName, hInstance)

http://msdn.microsoft.com/en-us/library/ms644899

We can do this by adding: classAtom = UnregisterClass(classAtom, hinst) but it must be added AFTER the window has been destroyed for example here is a fixed full version

# -- coding: utf-8 --

from win32api import *
from win32gui import *
import win32con
import sys, os
import struct
import time

# Class
class WindowsBalloonTip:
    def __init__(self, title, msg):
        message_map = { win32con.WM_DESTROY: self.OnDestroy,}

        # Register the window class.
        wc = WNDCLASS()
        hinst = wc.hInstance = GetModuleHandle(None)
        wc.lpszClassName = 'PythonTaskbar'
        wc.lpfnWndProc = message_map # could also specify a wndproc.
        classAtom = RegisterClass(wc)

        # Create the window.
        style = win32con.WS_OVERLAPPED | win32con.WS_SYSMENU
        self.hwnd = CreateWindow(classAtom, "Taskbar", style, 0, 0, win32con.CW_USEDEFAULT, win32con.CW_USEDEFAULT, 0, 0, hinst, None)
        UpdateWindow(self.hwnd)

        # Icons managment
        iconPathName = os.path.abspath(os.path.join( sys.path[0], 'balloontip.ico' ))
        icon_flags = win32con.LR_LOADFROMFILE | win32con.LR_DEFAULTSIZE
        try:
            hicon = LoadImage(hinst, iconPathName, win32con.IMAGE_ICON, 0, 0, icon_flags)
        except:
            hicon = LoadIcon(0, win32con.IDI_APPLICATION)
        flags = NIF_ICON | NIF_MESSAGE | NIF_TIP
        nid = (self.hwnd, 0, flags, win32con.WM_USER+20, hicon, 'Tooltip')

        # Notify
        Shell_NotifyIcon(NIM_ADD, nid)
        Shell_NotifyIcon(NIM_MODIFY, (self.hwnd, 0, NIF_INFO, win32con.WM_USER+20, hicon, 'Balloon Tooltip', msg, 200, title))
        # self.show_balloon(title, msg)
        time.sleep(5)

        # Destroy
        DestroyWindow(self.hwnd)
        classAtom = UnregisterClass(classAtom, hinst)
    def OnDestroy(self, hwnd, msg, wparam, lparam):
        nid = (self.hwnd, 0)
        Shell_NotifyIcon(NIM_DELETE, nid)
        PostQuitMessage(0) # Terminate the app.

# Function
def balloon_tip(title, msg):
    w=WindowsBalloonTip(title, msg)

# Main
if __name__ == '__main__':
    # Example
    balloon_tip('Lorem Ipsum', 'Neque porro quisquam est qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit...')
    balloon_tip('Example two', 'There is no one who loves pain itself, who seeks after it and wants to have it, simply because it is pain...')

There are issues on certain operating systems with the icon loading so if you want your own custom icon then change this line:

iconPathName = os.path.abspath(os.path.join( sys.path[0], 'balloontip.ico' ))

To something like:

iconPathName = "C:\myfolder\myicon.ico"