From 1b3b10d2ae7e40a611727dc9f8affbd2aff6bf9a Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Sun, 17 May 2020 13:05:12 -0700
Subject: [PATCH] Do not allow the sidebar to be dragged outside the window.
 (#1229)

---
 src/theme/book.js | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/theme/book.js b/src/theme/book.js
index a335324d..849f8cef 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -456,6 +456,11 @@ function playpen_text(playpen) {
     // Toggle sidebar
     sidebarToggleButton.addEventListener('click', function sidebarToggle() {
         if (html.classList.contains("sidebar-hidden")) {
+            var current_width = parseInt(
+                document.documentElement.style.getPropertyValue('--sidebar-width'), 10);
+            if (current_width < 150) {
+                document.documentElement.style.setProperty('--sidebar-width', '150px');
+            }
             showSidebar();
         } else if (html.classList.contains("sidebar-visible")) {
             hideSidebar();
@@ -476,7 +481,16 @@ function playpen_text(playpen) {
         html.classList.add('sidebar-resizing');
     }
     function resize(e) {
-        document.documentElement.style.setProperty('--sidebar-width', (e.clientX - sidebar.offsetLeft) + 'px');
+        var pos = (e.clientX - sidebar.offsetLeft);
+        if (pos < 20) {
+            hideSidebar();
+        } else {
+            if (html.classList.contains("sidebar-hidden")) {
+                showSidebar();
+            }
+            pos = Math.min(pos, window.innerWidth - 100);
+            document.documentElement.style.setProperty('--sidebar-width', pos + 'px');
+        }
     }
     //on mouseup remove windows functions mousemove & mouseup
     function stopResize(e) {