MDN говорит, что многое задаётся для SVG. и сеть предлагает такой вариант:
<head>
<script>
function addlistener() {
var scrollable = document.getElementsByClassName("scrollable-container")[0];
scrollable.addEventListener('mousedown', function() {
this.style.pointerEvents = "none";
document.elementFromPoint(event.clientX, event.clientY).click();
}, false);
document.getElementsByClassName("app")[0].addEventListener('mouseup', function(e) {
scrollable.style.pointerEvents = "all";
}, false);
}
</script>
<style>
body {
overflow-y: hidden;
}
.app {
overflow-y: hidden;
position: relative;
display: flex;
flex-direction: row;
z-index: 0;
}
.scrollable-container {
width: 100vw;
height: 100vh;
margin-left: -18px;
position: absolute;
overflow-y: scroll;
z-index: 10;
}
.scrollable-content {
width: 500px;
height: 1600px;
}
.non-scrollable-container {
flex: 1;
height: 100vh;
overflow-y: hidden;
}
.bridge {
width: 40px;
background: linear-gradient(white, black);
cursor: ew-resize;
height: 100vh;
}
#original {
background: linear-gradient(red, yellow);
height: 2100px;
}
#modified {
background: linear-gradient(blue, green);
height: 1600px;
}
</style>
</head>
<body onload="addlistener()">
<div class="app">
<div class="scrollable-container">
<div class="scrollable-content"></div>
</div>
<div class="non-scrollable-container">
<div id="original" class="codeBlock">
Content I want to select
</div>
</div>
<div class="bridge"></div>
<div class="non-scrollable-container">
<div id="modified" class="codeBlock">
Content I want to select
</div>
</div>
</div>
</body>
