From a409536ad01c46f7643588c75d8c819920f21778 Mon Sep 17 00:00:00 2001
From: Mario Pietsch <pmariojo@gmail.com>
Date: Sun, 27 Jun 2021 17:24:06 +0200
Subject: [PATCH] Prevent scrolling of the page when modals are displayed
 (#5816)

* prevent scroll-chaining in modals

* make body overflow hidden to prevent background scrolling
---
 core/modules/utils/dom/modal.js                           | 1 +
 editions/tw5.com/tiddlers/demonstrations/SampleWizard.tid | 2 +-
 themes/tiddlywiki/vanilla/base.tid                        | 3 +++
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/core/modules/utils/dom/modal.js b/core/modules/utils/dom/modal.js
index 58ffba6a4..58fe34efe 100644
--- a/core/modules/utils/dom/modal.js
+++ b/core/modules/utils/dom/modal.js
@@ -243,6 +243,7 @@ Modal.prototype.adjustPageClass = function() {
 	if(windowContainer) {
 		$tw.utils.toggleClass(windowContainer,"tc-modal-displayed",this.modalCount > 0);
 	}
+	$tw.utils.toggleClass(this.srcDocument.body,"tc-modal-prevent-scroll",this.modalCount > 0);
 };
 
 exports.Modal = Modal;
diff --git a/editions/tw5.com/tiddlers/demonstrations/SampleWizard.tid b/editions/tw5.com/tiddlers/demonstrations/SampleWizard.tid
index 5226b71ad..6ce1e3439 100644
--- a/editions/tw5.com/tiddlers/demonstrations/SampleWizard.tid
+++ b/editions/tw5.com/tiddlers/demonstrations/SampleWizard.tid
@@ -1,6 +1,6 @@
 created: 20140912145537860
 footer: <$button message="tm-close-tiddler">Close</$button>
-modified: 20140912145537861
+modified: 20210627054504823
 subtitle: I'm a modal wizard
 title: SampleWizard
 type: text/vnd.tiddlywiki
diff --git a/themes/tiddlywiki/vanilla/base.tid b/themes/tiddlywiki/vanilla/base.tid
index 256152404..e83cc86b9 100644
--- a/themes/tiddlywiki/vanilla/base.tid
+++ b/themes/tiddlywiki/vanilla/base.tid
@@ -1942,6 +1942,9 @@ html body.tc-body.tc-single-tiddler-window {
 	border-top: 1px solid <<colour modal-footer-border>>;
 }
 
+.tc-modal-prevent-scroll {
+	overflow: hidden;
+}
 
 /*
 ** Centered modals