Fix CalendarPicker timezone handling

CodenameOne/src/com/codename1/ui/spinner/CalendarPicker.java

@@ -26,6 +26,7 @@
 import com.codename1.ui.layouts.BorderLayout;
 
 import java.util.Date;
+import java.util.TimeZone;
 
 /**
  * A Calendar Picker widget.  Used by the picker.
@@ -58,4 +59,12 @@ public void setValue(Object value) {
 
     }
 
+    public void setTimeZone(TimeZone tmz) {
+        calendar.setTimeZone(tmz);
+    }
+
+    public TimeZone getTimeZone() {
+        return calendar.getTimeZone();
+    }
+
 }

maven/core-unittests/src/test/java/com/codename1/ui/spinner/CalendarPickerTest.java

@@ -0,0 +1,45 @@
+package com.codename1.ui.spinner;
+
+import com.codename1.ui.Calendar;
+import com.codename1.junit.UITestBase;
+import org.junit.jupiter.api.Test;
+
+import java.util.Date;
+import java.util.TimeZone;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class CalendarPickerTest extends UITestBase {
+
+    @Test
+    public void testTimezoneIssue() {
+        TimeZone originalDefault = TimeZone.getDefault();
+        try {
+            // Set default timezone to UTC-8 (PST) to simulate user environment
+            TimeZone.setDefault(TimeZone.getTimeZone("GMT-08:00"));
+
+            CalendarPicker picker = new CalendarPicker();
+
+            // Set the picker timezone to UTC to match the target date timezone
+            picker.setTimeZone(TimeZone.getTimeZone("UTC"));
+
+            java.util.Calendar calendar = java.util.Calendar.getInstance();
+            calendar.setTimeZone(TimeZone.getTimeZone("UTC"));
+            calendar.set(2023, java.util.Calendar.FEBRUARY, 10, 0, 0, 0);
+            calendar.set(java.util.Calendar.MILLISECOND, 0);
+            Date target = calendar.getTime();
+
+            picker.setValue(target);
+            Date picked = (Date) picker.getValue();
+            java.util.Calendar pickedCalendar = java.util.Calendar.getInstance(TimeZone.getTimeZone("UTC"));
+            pickedCalendar.setTime(picked);
+
+            assertEquals(calendar.get(java.util.Calendar.YEAR), pickedCalendar.get(java.util.Calendar.YEAR));
+            assertEquals(calendar.get(java.util.Calendar.MONTH), pickedCalendar.get(java.util.Calendar.MONTH));
+            assertEquals(calendar.get(java.util.Calendar.DAY_OF_MONTH), pickedCalendar.get(java.util.Calendar.DAY_OF_MONTH));
+
+        } finally {
+            TimeZone.setDefault(originalDefault);
+        }
+    }
+}