Update `QuillDialogTheme`

lib/src/models/themes/quill_dialog_theme.dart

@@ -1,8 +1,13 @@
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
-class QuillDialogTheme {
-  QuillDialogTheme(
-      {this.labelTextStyle, this.inputTextStyle, this.dialogBackgroundColor});
+class QuillDialogTheme with Diagnosticable {
+  const QuillDialogTheme({
+    this.labelTextStyle,
+    this.inputTextStyle,
+    this.dialogBackgroundColor,
+    this.shape,
+  });
 
   ///The text style to use for the label shown in the link-input dialog
   final TextStyle? labelTextStyle;
@@ -10,6 +15,48 @@ class QuillDialogTheme {
   ///The text style to use for the input text shown in the link-input dialog
   final TextStyle? inputTextStyle;
 
-  ///The background color for the [LinkDialog()]
+  ///The background color for the Quill dialog
   final Color? dialogBackgroundColor;
+
+  /// The shape of this dialog's border.
+  ///
+  /// Defines the dialog's [Material.shape].
+  ///
+  /// The default shape is a [RoundedRectangleBorder] with a radius of 4.0
+  final ShapeBorder? shape;
+
+  QuillDialogTheme copyWith({
+    TextStyle? labelTextStyle,
+    TextStyle? inputTextStyle,
+    Color? dialogBackgroundColor,
+    ShapeBorder? shape,
+  }) {
+    return QuillDialogTheme(
+      labelTextStyle: labelTextStyle ?? this.labelTextStyle,
+      inputTextStyle: inputTextStyle ?? this.inputTextStyle,
+      dialogBackgroundColor:
+          dialogBackgroundColor ?? this.dialogBackgroundColor,
+      shape: shape ?? this.shape,
+    );
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is QuillDialogTheme &&
+        other.labelTextStyle == labelTextStyle &&
+        other.inputTextStyle == inputTextStyle &&
+        other.dialogBackgroundColor == dialogBackgroundColor &&
+        other.shape == shape;
+  }
+
+  @override
+  int get hashCode => Object.hash(
+        labelTextStyle,
+        inputTextStyle,
+        dialogBackgroundColor,
+        shape,
+      );
 }