Fix positioning with document scroll

Picker.js

@@ -4,7 +4,7 @@
 // ...Or maybe a button with a popup menu
 // License: LGPLv3.0+
 // (c) Vitaliy Filippov 2019+
-// Version 2020-04-27
+// Version 2021-09-09
 
 import React from 'react';
 import ReactDOM from 'react-dom';
@@ -62,6 +62,8 @@ export default class Picker extends React.Component
             // calendar-box is calendar.js's class
             if (e == this.picker || e == n || /\bcalendar-box\b/.exec(e.className||''))
             {
+                ev.stopPropagation();
+                ev.preventDefault();
                 return;
             }
             e = e.parentNode;
@@ -91,7 +93,9 @@ export default class Picker extends React.Component
 
     renderPicker()
     {
-        return this.props.renderPicker();
+        return this.props.renderPicker({
+            blur: this.blur,
+        });
     }
 
     render()
@@ -129,13 +133,13 @@ export default class Picker extends React.Component
             if (this.props.autoHide && !this._blurSet)
             {
                 this._blurSet = true;
-                document.body.addEventListener('click', this.blurExt);
+                document.body.addEventListener('mousedown', this.blurExt);
             }
         }
         else if (this._blurSet)
         {
             this._blurSet = false;
-            document.body.removeEventListener('click', this.blurExt);
+            document.body.removeEventListener('mousedown', this.blurExt);
         }
     }
 
@@ -144,7 +148,7 @@ export default class Picker extends React.Component
         if (this._blurSet)
         {
             this._blurSet = false;
-            document.body.removeEventListener('click', this.blurExt);
+            document.body.removeEventListener('mousedown', this.blurExt);
         }
     }
 
@@ -178,13 +182,11 @@ export default class Picker extends React.Component
             direction = down ? 'down' : 'up';
         }
         let top = clientRect.top
-            + (window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop)
             - (document.documentElement.clientTop || document.body.clientTop || 0);
         const max_height = (direction == 'down' ? screen_height-top-(clientRect.height||0)-32 : top-32);
         const height = Math.ceil(popup_size.height < max_height ? popup_size.height : max_height);
         top = direction == 'down' ? (top + (clientRect.height||0)) : (top - height);
         let left = (clientRect.left
-            + (window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft)
             - (document.documentElement.clientLeft || document.body.clientLeft || 0));
         if (left + popup_size.width > screen_width)
         {