When customising my Python IDLE (in Options>Configure IDLE>Highlights>Choose color for:), if I choose a color from the palette and click on the button "Add to Custom Colors" multiple times, all my existing colors are replaced by a single color one by one, instead I feel it would be better if Python gave a popup saying something like "the selected color already exists in Custom colors".

IDLE has nothing to do with the operation of the color chooser.  IDLE calls a tkinter function that calls a tk functions that calls the OS Window Manager color chooser.  The choice you make is returned to IDLE as a color string that IDLE can later pass to tkinter and tk.  What you see on Windows, in your image is the MS Windows 10 color chooser.  The macOS color chooser is *completely* different.

The Windows Custom Color bar presumes that you make a small set of distinguishable custom colors.  The main use in IDLE would be if you create a custom backgound color that you want to use for multiple foreground/background pairs.  The use in Windows would be if you have a custom palette that you want to use for multiple applications.

Sorry for adding my file again. Can you please state the reason for
removing the file Mr. Terry J Reedy , was it because I haven't signed the
Contributor Agreement at that time? But now that I have signed it, can I
add the    https://bugs.python.org/file50298/python bug 1.png file again?

On Thu, 23 Sept 2021 at 20:58, Terry J. Reedy <report@bugs.python.org>
wrote:

>
> Change by Terry J. Reedy <tjreedy@udel.edu>:
>
>
> Removed file: https://bugs.python.org/file50297/python bug 1.png
>
> _______________________________________
> Python tracker <report@bugs.python.org>
> <https://bugs.python.org/issue45270>
> _______________________________________
>

I understand that, but is it possible to keep only unique colors in the
Custom Color palette, and when user chooses the exact same color to be in
the Custom Color palette it would return a pop up like "Color already in
Custom Color palette".

It would be better if the color strings which IDLE receives, are checked if
present already in Custom Colors, if not it then passes it to tkinter and
tk.

On Thu, 23 Sept 2021 at 21:08, Terry J. Reedy <report@bugs.python.org>
wrote:

>
> Terry J. Reedy <tjreedy@udel.edu> added the comment:
>
> IDLE has nothing to do with the operation of the color chooser.  IDLE
> calls a tkinter function that calls a tk functions that calls the OS Window
> Manager color chooser.  The choice you make is returned to IDLE as a color
> string that IDLE can later pass to tkinter and tk.  What you see on
> Windows, in your image is the MS Windows 10 color chooser.  The macOS color
> chooser is *completely* different.
>
> The Windows Custom Color bar presumes that you make a small set of
> distinguishable custom colors.  The main use in IDLE would be if you create
> a custom backgound color that you want to use for multiple
> foreground/background pairs.  The use in Windows would be if you have a
> custom palette that you want to use for multiple applications.
>
> ----------
> resolution:  -> third party
> stage:  -> resolved
> status: open -> closed
>
> _______________________________________
> Python tracker <report@bugs.python.org>
> <https://bugs.python.org/issue45270>
> _______________________________________
>

You added the same file twice.  Once was enough.

To repeat: IDLE has no knowledge of color chooser.  The Custom Colors bar is Windows specific.  There is no such thing on macOS.


PS: when responding by email, please delete the quoted message.  It is redundant and therefore noise when posted on the web page.