feat: 优化休息提醒弹窗，去除白框闪现

RestForm.cs

@@ -12,6 +12,18 @@ namespace TimerApp
 
         public event EventHandler? SkipRequested;
 
+        protected override CreateParams CreateParams
+        {
+            get
+            {
+                CreateParams cp = base.CreateParams;
+                // Turn on WS_EX_TOOLWINDOW style bit (0x80)
+                // 这可以防止窗口出现在 Alt-Tab 列表中，并减少任务栏闪烁风险
+                cp.ExStyle |= 0x80;
+                return cp;
+            }
+        }
+
         public RestForm()
         {
             InitializeComponent();
@@ -29,10 +41,11 @@ namespace TimerApp
             // Form 设置
             //
             this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
-            this.WindowState = FormWindowState.Maximized;
+            this.StartPosition = FormStartPosition.Manual;
+            this.Location = new System.Drawing.Point(-32000, -32000); // 初始位置在屏幕外
             this.TopMost = true;
             this.BackColor = System.Drawing.Color.Black;
-            this.Opacity = 0.90; // 90% 不透明度
+            this.Opacity = 0; // 初始隐藏，避免闪烁
             this.ShowInTaskbar = false;
             this.Name = "RestForm";
             this.Text = "Rest Now";
@@ -104,6 +117,28 @@ namespace TimerApp
             CenterControls();
         }
 
+        protected override void OnVisibleChanged(EventArgs e)
+        {
+            base.OnVisibleChanged(e);
+            if (this.Visible)
+            {
+                // 移回屏幕并最大化
+                this.Location = new Point(0, 0);
+                this.WindowState = FormWindowState.Maximized;
+                this.Refresh();
+                
+                // 延迟显示，确保布局调整完成
+                System.Windows.Forms.Timer t = new System.Windows.Forms.Timer();
+                t.Interval = 50;
+                t.Tick += (s, ev) => {
+                    t.Stop();
+                    t.Dispose();
+                    this.Opacity = 0.90;
+                };
+                t.Start();
+            }
+        }
+
         private void RestForm_Resize(object? sender, EventArgs e)
         {
             CenterControls();