Bug 1226272 - Part 4: Change the style which is for while dragging. r=jdescottes

MozReview-Commit-ID: 1JQ0bix8eZ

--HG--
extra : rebase_source : 24d2f411dd47382dac6897f1969d7632a496e13a

devtools/client/themes/toolbox.css

@@ -301,3 +301,14 @@
 #toolbox-container.tabs-reordering > .theme-body {
   pointer-events: none;
 }
+
+#toolbox-container.tabs-reordering .devtools-tab:not(.selected):hover .devtools-tab-line {
+  background: transparent;
+  opacity: 0;
+  transition: none;
+}
+
+#toolbox-container.tabs-reordering .devtools-tab.selected {
+  background-color: var(--theme-toolbar-hover);
+  z-index: 1;
+}