Fixes: U4-7564 "Save and publish" button menu skewed [7.4.0-beta]

So I tested it on a Surface and got the same result as you. We get this "bug" because of how bootstrap handles dropdowns on mobile/tablets. Bootstrap detect Suface as a tablet, and therefor pushed an element to the DOM called `dropdown-backdrop`. Disabling this will fix the "bug". But we need to be aware of this taken from http://getbootstrap.com/javascript/

>''"On mobile devices, opening a dropdown adds a `.dropdown-backdrop` as a tap area for closing dropdown menus when tapping outside the menu, a requirement for proper iOS support. This means that switching from an open dropdown menu to a different dropdown menu requires an extra tap on mobile."''

Since it's a very old Bootstrap we're using I took the liberty to just add `.btn-group .dropdown-backdrop` `display: none` so that the element wouldn't appear in the DOM anymore.

src/Umbraco.Web.UI.Client/src/less/hacks.less

@@ -31,6 +31,10 @@
   max-width: none !important;
 }
 
+.btn-group .dropdown-backdrop {
+    display: none;
+}
+
 /* loading animation for iframes and content pages */
 iframe, .content-column-body {
     background: center center url(../img/loader.gif) no-repeat;