Add a Unicode character browser extension to IDLE

The CharSelect extension adds a Character Browser command to the Edit
menu.  It opens a window for browsing Unicode blocks in a grid, viewing
a character's details, and searching by name or code point.  A character
can be inserted at the cursor of the editor or shell, or copied to the
clipboard.  On the detail tabs, a representation or normalization form
can be clicked to copy it or double-clicked to insert it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: serhiy-storchaka

Doc/library/idle.rst

@@ -170,6 +170,13 @@ Show Call Tip
 Show Surrounding Parens
    Highlight the surrounding parenthesis.
 
+Character Browser
+   Open a window to browse Unicode blocks and search for characters by name or code point.
+   Double-click a character, or select it and press Insert, to insert it into the current window.
+   Press Copy character to copy it to the clipboard.
+   The detail tabs show the character's representations, such as escapes, UTF-8 bytes, XML and HTML references, and normalization forms.
+   Click a highlighted value to copy it, or double-click it to insert it.
+
 .. _format-menu:
 
 Format menu (Editor window only)

Lib/idlelib/News3.txt

@@ -4,6 +4,12 @@ Released on 2026-10-01
 =========================
 
 
+gh-152940: Add a Unicode character browser to IDLE.  It appears on the
+Edit menu as "Character Browser" and can browse Unicode blocks, search
+for characters by name or code point, insert a character into the
+window, and copy a character to the clipboard.  Patch by Serhiy
+Storchaka.
+
 gh-152745:  When "Run... Customized" with "Restart shell" unchecked
 while Shell is running code, including waiting for an input('prompt:')
 response, just report that the shell is executing instead of