When Cryptpad.clearTooltips() gets called, don't clear tooltips unless their associated element has gone missing so it won't clear a tip someone is trying to read.

www/common/common-interface.js

@@ -301,7 +301,15 @@ define([
     // Tooltips
 
     UI.clearTooltips = function () {
-        $('.tippy-popper').remove();
+        // If an element is removed from the UI while a tooltip is applied on that element, the tooltip will get hung
+        // forever, this is a solution which just searches for tooltips which have no corrisponding element and removes
+        // them.
+        var win = $('#pad-iframe')[0].contentWindow;
+        $('.tippy-popper').each(function (i, el) {
+            if (win.$('[aria-describedby=' + el.getAttribute('id') + ']').length === 0) {
+                el.remove();
+            }
+        });
     };
 
     UI.addTooltips = function () {