Merge from master

src/vs/base/browser/ui/selectBox/selectBoxCustom.css

@@ -16,8 +16,28 @@
 
 .monaco-select-box-dropdown-container {
 	display: none;
+	-webkit-box-sizing:	border-box;
+	-o-box-sizing:		border-box;
+	-moz-box-sizing:	border-box;
+	-ms-box-sizing:		border-box;
+	box-sizing:			border-box;
 }
 
+.monaco-select-box-dropdown-container > .select-box-details-pane > .select-box-description-markdown * {
+	margin: 0;
+}
+
+.monaco-select-box-dropdown-container > .select-box-details-pane > .select-box-description-markdown a:focus {
+	outline: 1px solid -webkit-focus-ring-color;
+	outline-offset: -1px;
+}
+
+.monaco-select-box-dropdown-container > .select-box-details-pane > .select-box-description-markdown code {
+	line-height: 15px; /** For some reason, this is needed, otherwise <code> will take up 20px height */
+	font-family: Menlo, Monaco, Consolas, "Droid Sans Mono", "Courier New", monospace, "Droid Sans Fallback";
+}
+
+
 .monaco-select-box-dropdown-container.visible {
 	display: flex;
 	flex-direction: column;
@@ -42,11 +62,19 @@
 	box-sizing:			border-box;
 }
 
+.monaco-select-box-dropdown-container > .select-box-details-pane {
+	padding: 5px;
+}
+
 .hc-black .monaco-select-box-dropdown-container > .select-box-dropdown-list-container {
 	padding-top: var(--dropdown-padding-top);
 	padding-bottom: var(--dropdown-padding-bottom);
 }
 
+.monaco-select-box-dropdown-container > .select-box-dropdown-list-container .monaco-list .monaco-list-row {
+	cursor: pointer;
+}
+
 .monaco-select-box-dropdown-container > .select-box-dropdown-list-container .monaco-list .monaco-list-row > .option-text {
 	text-overflow: ellipsis;
 	overflow: hidden;
@@ -54,6 +82,18 @@
 	white-space: nowrap;
 }
 
+/* Accepted CSS hiding technique for accessibility reader text  */
+/* https://webaim.org/techniques/css/invisiblecontent/ */
+
+.monaco-select-box-dropdown-container > .select-box-dropdown-list-container .monaco-list .monaco-list-row > .visually-hidden {
+		position: absolute;
+		left: -10000px;
+		top: auto;
+		width: 1px;
+		height: 1px;
+		overflow: hidden;
+}
+
 .monaco-select-box-dropdown-container > .select-box-dropdown-container-width-control {
 	flex: 1 1 auto;
 	align-self: flex-start;