fix: fix some status logic.

src/Ursa/Controls/DateTimePicker/CalendarDayButton.cs

@@ -76,7 +76,7 @@ public class CalendarDayButton : ContentControl
         set
         {
             _isStartDate = value;
-            SetPseudoClass(PC_StartDate);
+            SetPseudoClass(PC_StartDate, value);
         }
     }
 
@@ -86,7 +86,7 @@ public class CalendarDayButton : ContentControl
         set
         {
             _isEndDate = value;
-            SetPseudoClass(PC_EndDate);
+            SetPseudoClass(PC_EndDate, value);
         }
     }
 
@@ -96,7 +96,7 @@ public class CalendarDayButton : ContentControl
         set
         {
             _isPreviewStartDate = value;
-            PseudoClasses.Set(PC_PreviewStartDate, value);
+            SetPseudoClass(PC_PreviewStartDate, value);
         }
     }
 
@@ -106,7 +106,7 @@ public class CalendarDayButton : ContentControl
         set
         {
             _isPreviewEndDate = value;
-            PseudoClasses.Set(PC_PreviewEndDate, value);
+            SetPseudoClass(PC_PreviewEndDate, value);
         }
     }
 
@@ -116,7 +116,7 @@ public class CalendarDayButton : ContentControl
         set
         {
             _isInRange = value;
-            PseudoClasses.Set(PC_InRange, value);
+            SetPseudoClass(PC_InRange, value);
         }
     }
 
@@ -126,7 +126,7 @@ public class CalendarDayButton : ContentControl
         set
         {
             _isSelected = value;
-            SetPseudoClass(PseudoClassName.PC_Selected);
+            SetPseudoClass(PseudoClassName.PC_Selected, value);
         }
     }
 
@@ -191,15 +191,15 @@ public class CalendarDayButton : ContentControl
         }
     }
 
-    private void SetPseudoClass(string s)
+    private void SetPseudoClass(string s, bool value)
     {
-        if (_pseudoClasses.Contains(s))
+        if (_pseudoClasses.Contains(s) && value)
         {
             foreach (var pc in _pseudoClasses)
             {
                 PseudoClasses.Set(pc, false);
             }
         }
-        PseudoClasses.Set(s, true);
+        PseudoClasses.Set(s, value);
     }
 }

src/Ursa/Controls/DateTimePicker/CalendarView.cs

@@ -553,20 +553,37 @@ public class CalendarView : TemplatedControl
         }
     }
 
-    public void ClearSelection()
+    public void ClearSelection(bool start = true, bool end = true)
     {
-        _start = null;
+        if (start)
-        _end = null;
+        {
-        _previewStart = null;
+            _previewStart = null;
-        _previewEnd = null;
+            _start = null;
+        }
+
+        if (end)
+        {
+            _previewEnd = null;
+            _end = null;
+        }
+        
         if (_monthGrid?.Children is null) return;
         foreach (var child in _monthGrid.Children)
         {
             if (child is not CalendarDayButton button) continue;
-            button.IsStartDate = false;
+            if (start)
-            button.IsEndDate = false;
+            {
-            button.IsInRange = false;
+                button.IsPreviewStartDate = false;
+                button.IsStartDate = false;
+            }
+            if (end)
+            {
+                button.IsEndDate = false;
+                button.IsInRange = false;
+            }
+            button.IsPreviewEndDate = false;
         }
+        UpdateDayButtons();
     }
 
     protected override void OnPointerExited(PointerEventArgs e)

src/Ursa/Controls/DateTimePicker/DateRangePicker.cs

@@ -302,8 +302,8 @@ public class DateRangePicker : DatePickerBase
         if (string.IsNullOrEmpty(textBox?.Text))
         {
             SetCurrentValue(property, null);
-            _startCalendar?.ClearSelection();
+            _startCalendar?.ClearSelection(start: true);
-            _endCalendar?.ClearSelection();
+            _endCalendar?.ClearSelection(end: true);
         }
         else if (DisplayFormat is null || DisplayFormat.Length == 0)
         {