Hi Alan,
it works using ‘BackSpace’ and ‘Delete’!
There is no ‘BackSpace’ key on Mac, so I didn’t come up with this key before,
thanks for your advise and answer :)
B.R.
Yuehua
> On Dec 9, 2015, at 03:54, Alan Gauld <alan.ga...@btinternet.com> wrote:
>
> On 08/12/15 15:08, Yuehua HU wrote:
>
>> I’ve tried to write 'user changing their mind and blanking the field’ case,
>> but it seems not working…
>> Did I use '<KeyPress-Delete>’ wrong?
>
> Delete is the key that deletes the character to the right of cursor.
> Did you maybe mean to use <'Keypress-BackSpace'>? Or even both of them?
>
>> ...Why should we use a parameter in the function 'greyText(e)’ ?
>
> Because the bind mechanism passes the event object as an argument
> and expects the function to accept it even if its not used.
> [Aside: This is annoying since the command attribute of widgets expects
> a function with no arguments! To get round that set a default value of None:
>
> def aCallBack(event=None):...
>
> then you can use aCallBack() in either scenario.
> ]
>
> HTH
>
>> #######################
>> import Tkinter
>>
>> def checkEnterStrLen(e):
>> if len(var.get())==0:
>> entry.config(fg= 'grey')
>> entry.insert(0, 'help text')
>>
>> def greyText(e):
>> entry.config(fg = 'grey')
>>
>> def startEntry(e):
>> entry.delete(0,Tkinter.END)
>> entry.config(fg = 'black')
>> entry.unbind('<Key>')
>>
>> top = Tkinter.Tk()
>>
>> var = Tkinter.StringVar()
>> entry = Tkinter.Entry(top, textvariable = var)
>> entry.insert(0,'help text')
>>
>> entry.bind('<Button-1>', greyText)
>> entry.bind('<KeyPress-Delete>',checkEnterStrLen)
>> entry.bind('<Key>',startEntry)
>>
>> entry.pack()
>>
>> top.mainloop()
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
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