Error in gui programming in python using tkinter
Question: 
    #!/usr/bin/python
    # -*- coding: iso-8859-1 -*-
    
    import Tkinter
    
    class simpleapp_tk(Tkinter.Tk):
        def __init__(self,parent):
            Tkinter.Tk.__init__(self,parent)
            self.parent=parent
        def initialize(self):
            self.grid()
    
            self.entry=Tkinter.Entry(self)
            self.entry.grid(column=0,row=0,sticky='EW')
            self.entry.bind("<Return>",self.OnPressEnter)
    
            button=Tkinter.Button(self,test="Post it!",command=self.OnButtonClick)
            button.grid(column=1,row=0)
    
            label=Tkinter.Label(self,anchor="w",fg="white",bg="blue")
            label=grid(column=0,row=1,columnspan=2,sticky='EW')
    
            self.grid_columnconfigure(0,weight=1)
    
        def OnButtonClick(self):
            print "you clicked the button!"
    
        def OnPressEnter(self,event):
            print "you pressed enter!"
    
    if __name__=="__main__":
        app=simpleapp_tk(None)
        app.title('poster')
        app.mainloop()
    

I wrote this program so as to make a box to input text and a button, but it
shows nothing apart from a window. Where is the error?


Answer: The main issue was that you forgot to call `app.initialize()`, but you also
had a couple of typos. I've pointed out where in the comments in this fixed
version.

    
    
    import Tkinter
    
    class simpleapp_tk(Tkinter.Tk):
        def __init__(self,parent):
            Tkinter.Tk.__init__(self,parent)
            self.parent=parent
        def initialize(self):
            self.grid()
    
            self.entry=Tkinter.Entry(self)
            self.entry.grid(column=0,row=0,sticky='EW')
            self.entry.bind("<Return>",self.OnPressEnter)
    
            button=Tkinter.Button(self,text="Post it!",command=self.OnButtonClick)
            # the text keyword argument was mis-typed as 'test'
    
            button.grid(column=1,row=0)
    
            label=Tkinter.Label(self,anchor="w",fg="white",bg="blue")
            label.grid(column=0,row=1,columnspan=2,sticky='EW')
            # the . in label.grid was mis-typed as '='
    
            self.grid_columnconfigure(0,weight=1)
    
        def OnButtonClick(self):
            print "you clicked the button!"
    
        def OnPressEnter(self,event):
            print "you pressed enter!"
    
    if __name__=="__main__":
        app=simpleapp_tk(None)
        app.title('poster')
        app.initialize() # you forgot this
        app.mainloop()
    

