Bug 1375114 - Disable selection entirely in the #categories navigation panel. r=chutten

MozReview-Commit-ID: 9mucWUigXSG

toolkit/content/aboutTelemetry.css

@@ -17,6 +17,7 @@ body {
   padding-top: 0px;
   overflow-y: auto;
   margin-bottom: 42px;
+  -moz-user-select: none;
 }
 
 .main-content.search > section > *:not(.data) {
@@ -122,7 +123,6 @@ body[dir=rtl] .dropdown {
   padding: 8px 0px;
   padding-inline-start: 16px;
   display: none;
-  -moz-user-select: none;
 }
 
 .category-subsection.selected {

toolkit/content/aboutTelemetry.js

@@ -1981,9 +1981,6 @@ function show(selected) {
   });
   selected_section.classList.add("active");
 
-  // Hack because subsection text appear selected. See Bug 1375114.
-  document.getSelection().empty();
-
   adjustHeaderState();
   displayProcessesSelector(selectedValue);
   adjustSearchState();
@@ -2008,7 +2005,6 @@ function showSubSection(selected) {
   let title = selected.parentElement.querySelector(".category-name").textContent;
   let subsection = selected.textContent;
   document.getElementById("sectionTitle").textContent = title + " - " + subsection;
-  document.getSelection().empty(); // prevent subsection text selection
   changeUrlPath(subsection, true);
 }