The image manager dialog do not resize properly in Chrome when the screen resolution is 1920x1080 and the Windows zoom level is 125%-150%-175%.

In Internet Explorer, all dialogs have scrolls - tested on 4k screen with 150% zoom.

See the attachments.

Workaround:

<script>
    function OnClientCommandExecuted(editor, args) {
        if (editor.get_dialogOpener()) {
            var commandName = args.get_commandName();

            if (editor.get_dialogOpener()._getDialogContainer) {
                dialogReference = editor.get_dialogOpener()._getDialogContainer(commandName);
                setTimeout(function () {
                    var dialogContainerHeight = parseInt(editor.get_dialogOpener()._getDialogContainer(commandName).get_contentElement().style.height);
                    dialogReference.set_height(dialogContainerHeight + 40);
                    dialogReference.get_contentElement().removeAttribute("style");
                    dialogReference.get_contentElement().style.height = dialogContainerHeight + 5 + "px";
                          
                }, 1000);
                        
            }
        }
    }
</script>
<telerik:RadEditor ID="RadEditor1" runat="server"  OnClientCommandExecuted="OnClientCommandExecuted">
    <ImageManager ViewPaths="~/" />
</telerik:RadEditor>