Example 15-6 implements a handful of utility pop-up windows in a module, in case they ever prove useful in other programs. Note that the same windows utility module is imported here, to give a common look-and-feel to the popups (icons, titles, and so on).

Example 15-6. PP3E\Internet\Email\PyMailGui\popuputil.py

################################################################ # utility windows - may be useful in other programs ###############################################################

from Tkinter import *
from PP3E.Gui.Tools.windows import PopupWindow

class HelpPopup(PopupWindow):
    """
    custom Toplevel that shows help text as scrolled text
    source button runs a passed-in callback handler
    alternative: use HTML file and webbrowser module
    """
    myfont = 'system' # customizable

    def __init__(self, appname, helptext, iconfile=None, showsource=lambda:0) :  
        PopupWindow.__init__(self, appname, 'Help', iconfile)
        from ScrolledText import ScrolledText                       # a nonmodal dialog
        bar = Frame(self)          # pack first=clip last
        bar.pack(side=BOTTOM, fill=X)
        code = Button(bar, bg='beige', text="Source", command=showsource)
        quit = Button(bar, bg='beige', text="Cancel", command=self.destroy) 
        code.pack(pady=1, side=LEFT)
        quit.pack(pady=1, side=LEFT)
        text = ScrolledText(self)      # add
Text + scrollbar
        text.config(font=self.myfont, width=70)                              # too big for showinfo
        text.config(bg='steelblue', fg='white')                            # erase on btn or return
        text.insert('0.0', helptext)
        text.pack(expand=YES, fill=BOTH)
        self.bind("<Return>", (lambda event: self.destroy()))

    def askPasswordWindow(appname, prompt):
        """
        modal dialog to input password string
        getpass.getpass uses stdin, not GUI
        tkSimpleDialog.askstring echos input
        """
        win = PopupWindow(appname,
'Prompt')                            # a configured Toplevel
        Label(win, text=prompt).pack(side=LEFT)
        entvar = StringVar(win)
        ent = Entry(win, textvariable=entvar, show='*')       # display * for input
        ent.pack(side=RIGHT, expand=YES, fill=X)
        ent.bind('<Return>', lambda event: win.destroy())
        ent.focus_set(); win.grab_set(); win.wait_window()
        win.update()                # update forces redraw
        return entvar.get()         # ent widget is now gone

    class BusyBoxWait(PopupWindow):
        """
        pop up blocking wait message box: thread waits
        main GUI event thread stays alive during wait
        but GUI is inoperable during this wait state;
        uses quit redef here because lower, not leftmost;
        """
        def __init__(self, appname, message):
            PopupWindow.__init__(self, appname, 'Busy')
            self.protocol('WM_DELETE_WINDOW', lambda:0)      # ignore deletes
            label = Label(self,
text=message + '...')               # win.quit() to erase
            label.config(height=10, width=40, cursor='watch')           # busy cursor
            label.pack()
            self.makeModal()
            self.message, self.label = message, label
        def makeModal(self):
            self.focus_set()        # grab application
            self.grab_set()         # wait for threadexit
        def changeText(self, newtext):
            self.label.config(text=self.message + ': ' + newtext)
        def quit(self):
            self.destroy()          # don't verify quit

    class BusyBoxNowait(BusyBoxWait):
        """
        pop up nonblocking wait window
        call changeText to show progress, quit to close
        """
        def makeModal(self):
            pass

    if __name__ == '__main__':
        HelpPopup('spam', 'See figure 1...\n')
        print askPasswordWindow('spam', 'enter password')
        raw_input('Enter to exit')