fixed #1162: In main window Esc will close window

ShareX/Forms/MainForm.cs

@@ -876,6 +876,17 @@ protected override void SetVisibleCore(bool value)
             base.SetVisibleCore(value);
         }
 
+        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
+        {
+            if (keyData == Keys.Escape)
+            {
+                Close();
+                return true;
+            }
+
+            return base.ProcessCmdKey(ref msg, keyData);
+        }
+
         private void MainForm_Shown(object sender, EventArgs e)
         {
             AfterShownJobs();