diff --git a/Bin/net40/SunnyUI.Demo.exe b/Bin/net40/SunnyUI.Demo.exe
index ee06ac97..330ed424 100644
Binary files a/Bin/net40/SunnyUI.Demo.exe and b/Bin/net40/SunnyUI.Demo.exe differ
diff --git a/Bin/net40/SunnyUI.dll b/Bin/net40/SunnyUI.dll
index 57875d4e..1f25dc2d 100644
Binary files a/Bin/net40/SunnyUI.dll and b/Bin/net40/SunnyUI.dll differ
diff --git a/Bin/net5.0-windows/SunnyUI.dll b/Bin/net5.0-windows/SunnyUI.dll
index 2c71bc09..3ae5edce 100644
Binary files a/Bin/net5.0-windows/SunnyUI.dll and b/Bin/net5.0-windows/SunnyUI.dll differ
diff --git a/Bin/net5.0-windows/ref/SunnyUI.dll b/Bin/net5.0-windows/ref/SunnyUI.dll
index e006f053..0ce64b45 100644
Binary files a/Bin/net5.0-windows/ref/SunnyUI.dll and b/Bin/net5.0-windows/ref/SunnyUI.dll differ
diff --git a/Bin/netcoreapp3.1/SunnyUI.dll b/Bin/netcoreapp3.1/SunnyUI.dll
index 10f70501..afcc5179 100644
Binary files a/Bin/netcoreapp3.1/SunnyUI.dll and b/Bin/netcoreapp3.1/SunnyUI.dll differ
diff --git a/SunnyUI/Forms/UIFormHelper.cs b/SunnyUI/Forms/UIFormHelper.cs
index d29db7b0..5d18e417 100644
--- a/SunnyUI/Forms/UIFormHelper.cs
+++ b/SunnyUI/Forms/UIFormHelper.cs
@@ -148,7 +148,7 @@ namespace Sunny.UI
         public static bool ShowMessageDialog(this Form form, string message, string title, bool isShowCancel, UIStyle style)
         {
             UIMessageForm frm = new UIMessageForm();
-            frm.TopMost = form.TopMost;
+            frm.TopMost = form != null && form.TopMost;
             frm.ShowMessage(message, title, isShowCancel, style);
             frm.ShowDialog();
             bool isOk = frm.IsOK;
@@ -252,7 +252,7 @@ namespace Sunny.UI
 
     public static class UIInputDialog
     {
-        private static bool InputStringDialog(ref string value, bool checkEmpty = true, string desc = "请输入字符串：", UIStyle style = UIStyle.Blue, bool topMost = false)
+        public static bool InputStringDialog(ref string value, bool checkEmpty = true, string desc = "请输入字符串：", UIStyle style = UIStyle.Blue, bool topMost = false)
         {
             UIInputForm frm = new UIInputForm();
             frm.TopMost = topMost;
@@ -273,20 +273,20 @@ namespace Sunny.UI
 
         public static bool InputStringDialog(this UIForm form, ref string value, bool checkEmpty = true, string desc = "请输入字符串：")
         {
-            return InputStringDialog(ref value, checkEmpty, desc, form.Style, form.TopMost);
+            return InputStringDialog(ref value, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputStringDialog(this UIPage form, ref string value, bool checkEmpty = true, string desc = "请输入字符串：")
         {
-            return InputStringDialog(ref value, checkEmpty, desc, form.Style, form.TopMost);
+            return InputStringDialog(ref value, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputStringDialog(this Form form, ref string value, bool checkEmpty = true, string desc = "请输入字符串：", UIStyle style = UIStyle.Blue)
         {
-            return InputStringDialog(ref value, checkEmpty, desc, style, form.TopMost);
+            return InputStringDialog(ref value, checkEmpty, desc, style, form != null && form.TopMost);
         }
 
-        private static bool InputPasswordDialog(ref string value, bool checkEmpty = true, string desc = "请输入密码：", UIStyle style = UIStyle.Blue, bool topMost = false)
+        public static bool InputPasswordDialog(ref string value, bool checkEmpty = true, string desc = "请输入密码：", UIStyle style = UIStyle.Blue, bool topMost = false)
         {
             UIInputForm frm = new UIInputForm();
             frm.TopMost = topMost;
@@ -307,20 +307,20 @@ namespace Sunny.UI
 
         public static bool InputPasswordDialog(this UIForm form, ref string value, bool checkEmpty = true, string desc = "请输入密码：")
         {
-            return InputPasswordDialog(ref value, checkEmpty, desc, form.Style, form.TopMost);
+            return InputPasswordDialog(ref value, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputPasswordDialog(this UIPage form, ref string value, bool checkEmpty = true, string desc = "请输入密码：")
         {
-            return InputPasswordDialog(ref value, checkEmpty, desc, form.Style, form.TopMost);
+            return InputPasswordDialog(ref value, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputPasswordDialog(this Form form, ref string value, bool checkEmpty = true, string desc = "请输入密码：", UIStyle style = UIStyle.Blue)
         {
-            return InputPasswordDialog(ref value, checkEmpty, desc, style, form.TopMost);
+            return InputPasswordDialog(ref value, checkEmpty, desc, style, form != null && form.TopMost);
         }
 
-        private static bool InputIntegerDialog(ref int value, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue, bool topMost = false)
+        public static bool InputIntegerDialog(ref int value, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue, bool topMost = false)
         {
             UIInputForm frm = new UIInputForm();
             frm.TopMost = topMost;
@@ -340,7 +340,7 @@ namespace Sunny.UI
             return false;
         }
 
-        private static bool InputIntegerDialog(ref int value, int minimum, int maximum, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue, bool topMost = false)
+        public static bool InputIntegerDialog(ref int value, int minimum, int maximum, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue, bool topMost = false)
         {
             UIInputForm frm = new UIInputForm();
             frm.TopMost = topMost;
@@ -367,35 +367,35 @@ namespace Sunny.UI
 
         public static bool InputIntegerDialog(this UIForm form, ref int value, bool checkEmpty = true, string desc = "请输入数字：")
         {
-            return InputIntegerDialog(ref value, checkEmpty, desc, form.Style, form.TopMost);
+            return InputIntegerDialog(ref value, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputIntegerDialog(this UIPage form, ref int value, bool checkEmpty = true, string desc = "请输入数字：")
         {
-            return InputIntegerDialog(ref value, checkEmpty, desc, form.Style, form.TopMost);
+            return InputIntegerDialog(ref value, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputIntegerDialog(this Form form, ref int value, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue)
         {
-            return InputIntegerDialog(ref value, checkEmpty, desc, style, form.TopMost);
+            return InputIntegerDialog(ref value, checkEmpty, desc, style, form != null && form.TopMost);
         }
 
         public static bool InputIntegerDialog(this UIForm form, ref int value, int minimum, int maximum, bool checkEmpty = true, string desc = "请输入数字：")
         {
-            return InputIntegerDialog(ref value, minimum, maximum, checkEmpty, desc, form.Style, form.TopMost);
+            return InputIntegerDialog(ref value, minimum, maximum, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputIntegerDialog(this UIPage form, ref int value, int minimum, int maximum, bool checkEmpty = true, string desc = "请输入数字：")
         {
-            return InputIntegerDialog(ref value, minimum, maximum, checkEmpty, desc, form.Style, form.TopMost);
+            return InputIntegerDialog(ref value, minimum, maximum, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputIntegerDialog(this Form form, ref int value, int minimum, int maximum, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue)
         {
-            return InputIntegerDialog(ref value, minimum, maximum, checkEmpty, desc, style, form.TopMost);
+            return InputIntegerDialog(ref value, minimum, maximum, checkEmpty, desc, style, form != null && form.TopMost);
         }
 
-        private static bool InputDoubleDialog(ref double value, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue, bool topMost = false)
+        public static bool InputDoubleDialog(ref double value, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue, bool topMost = false)
         {
             UIInputForm frm = new UIInputForm();
             frm.TopMost = topMost;
@@ -416,7 +416,7 @@ namespace Sunny.UI
             return false;
         }
 
-        private static bool InputDoubleDialog(ref double value, double minimum, double maximum, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue, bool topMost = false)
+        public static bool InputDoubleDialog(ref double value, double minimum, double maximum, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue, bool topMost = false)
         {
             UIInputForm frm = new UIInputForm();
             frm.TopMost = topMost;
@@ -443,32 +443,32 @@ namespace Sunny.UI
 
         public static bool InputDoubleDialog(this UIForm form, ref double value, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：")
         {
-            return InputDoubleDialog(ref value, decimals, checkEmpty, desc, form.Style, form.TopMost);
+            return InputDoubleDialog(ref value, decimals, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputDoubleDialog(this UIPage form, ref double value, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：")
         {
-            return InputDoubleDialog(ref value, decimals, checkEmpty, desc, form.Style, form.TopMost);
+            return InputDoubleDialog(ref value, decimals, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputDoubleDialog(this Form form, ref double value, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue)
         {
-            return InputDoubleDialog(ref value, decimals, checkEmpty, desc, style, form.TopMost);
+            return InputDoubleDialog(ref value, decimals, checkEmpty, desc, style, form != null && form.TopMost);
         }
 
         public static bool InputDoubleDialog(this UIForm form, ref double value, double minimum, double maximum, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：")
         {
-            return InputDoubleDialog(ref value, minimum, maximum, decimals, checkEmpty, desc, form.Style, form.TopMost);
+            return InputDoubleDialog(ref value, minimum, maximum, decimals, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputDoubleDialog(this UIPage form, ref double value, double minimum, double maximum, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：")
         {
-            return InputDoubleDialog(ref value, minimum, maximum, decimals, checkEmpty, desc, form.Style, form.TopMost);
+            return InputDoubleDialog(ref value, minimum, maximum, decimals, checkEmpty, desc, form.Style, form != null && form.TopMost);
         }
 
         public static bool InputDoubleDialog(this Form form, ref double value, double minimum, double maximum, int decimals = 2, bool checkEmpty = true, string desc = "请输入数字：", UIStyle style = UIStyle.Blue)
         {
-            return InputDoubleDialog(ref value, minimum, maximum, decimals, checkEmpty, desc, style, form.TopMost);
+            return InputDoubleDialog(ref value, minimum, maximum, decimals, checkEmpty, desc, style, form != null && form.TopMost);
         }
     }
 
@@ -497,7 +497,7 @@ namespace Sunny.UI
 
         public static bool ShowSelectDialog(this Form form, ref int selectIndex, IList items, UIStyle style = UIStyle.Blue)
         {
-            return form.ShowSelectDialog(ref selectIndex, items, UILocalize.SelectTitle, "", style, form.TopMost);
+            return form.ShowSelectDialog(ref selectIndex, items, UILocalize.SelectTitle, "", style, form != null && form.TopMost);
         }
 
         public static bool ShowSelectDialog(this UIForm form, ref int selectIndex, IList items)
@@ -512,12 +512,12 @@ namespace Sunny.UI
 
         public static bool ShowSelectDialog(this UIForm form, ref int selectIndex, IList items, string title, string description)
         {
-            return form.ShowSelectDialog(ref selectIndex, items, title, description, form.Style, form.TopMost);
+            return form.ShowSelectDialog(ref selectIndex, items, title, description, form.Style, form != null && form.TopMost);
         }
 
         public static bool ShowSelectDialog(this UIPage form, ref int selectIndex, IList items, string title, string description)
         {
-            return form.ShowSelectDialog(ref selectIndex, items, title, description, form.Style, form.TopMost);
+            return form.ShowSelectDialog(ref selectIndex, items, title, description, form.Style, form != null && form.TopMost);
         }
     }