make errorText of DialogTextField selectable (#11013)

Signed-off-by: 21pages <sunboeasy@gmail.com>

flutter/lib/common/widgets/dialog.dart

@@ -412,7 +412,9 @@ class DialogTextField extends StatelessWidget {
     return Row(
       children: [
         Expanded(
-          child: TextField(
+          child: Column(
+            children: [
+              TextField(
                 decoration: InputDecoration(
                   labelText: title,
                   hintText: hintText,
@@ -420,8 +422,6 @@ class DialogTextField extends StatelessWidget {
                   suffixIcon: suffixIcon,
                   helperText: helperText,
                   helperMaxLines: 8,
-              errorText: errorText,
-              errorMaxLines: 8,
                 ),
                 controller: controller,
                 focusNode: focusNode,
@@ -430,6 +430,20 @@ class DialogTextField extends StatelessWidget {
                 keyboardType: keyboardType,
                 inputFormatters: inputFormatters,
                 maxLength: maxLength,
+              ),
+              if (errorText != null)
+                Align(
+                  alignment: Alignment.centerLeft,
+                  child: SelectableText(
+                    errorText!,
+                    style: TextStyle(
+                      color: Theme.of(context).colorScheme.error,
+                      fontSize: 12,
+                    ),
+                    textAlign: TextAlign.left,
+                  ).paddingOnly(top: 8, left: 12),
+                ),
+            ],
           ).workaroundFreezeLinuxMint(),
         ),
       ],