Add vendor prefixes for user-select

.stylelintrc

@@ -64,7 +64,7 @@
       "number-leading-zero":"always",
       "number-no-trailing-zeros":true,
       "property-no-unknown":true,
-      "property-no-vendor-prefix":true,
+      "property-no-vendor-prefix": [true, { "ignoreProperties": ["user-select"] }],
       "rule-empty-line-before":[
          "always-multi-line",
          {

app/assets/stylesheets/pages/boards.scss

@@ -7,6 +7,9 @@
   opacity: 1 !important;
 
   * {
+    -webkit-user-select: none;
+    -moz-user-select: none;
+    -ms-user-select: none;
     user-select: none;
     // !important to make sure no style can override this when dragging
     cursor: grabbing !important;

app/assets/stylesheets/pages/search.scss

@@ -84,6 +84,9 @@ input[type='checkbox']:hover {
 
     .search-icon {
       transition: color $default-transition-duration;
+      -webkit-user-select: none;
+      -moz-user-select: none;
+      -ms-user-select: none;
       user-select: none;
     }
 

changelogs/unreleased/winh-boards-drag-selection.yml

+---
+title: Prevent text selection when dragging in issue boards
+merge_request: 27724
+author:
+type: fixed