Fix few dashboard panel issues (#801)

* home tab is shown by default when the dashboard is opened

* add scroll bar when tab list is overflow

* fix regression in other tab panels

* address comments

src/sql/base/browser/ui/panel/media/panel.css

@@ -29,6 +29,8 @@ panel {
 	padding: 0;
 	justify-content: flex-start;
 	line-height: 35px;
+	white-space: nowrap;
+	flex: 1;
 }
 
 .tabbedPanel .tabList .tab {
@@ -61,7 +63,7 @@ panel {
 }
 
 .composite.title .title-actions {
-	flex: 1;
+	flex: 1 1 auto;
 }
 
 .tab > .tabLabel.active {
@@ -87,6 +89,10 @@ panel {
 	height: 100%;
 }
 
+.tabbedPanel.vertical .tabList {
+	flex-direction: column;
+}
+
 .tabbedPanel > .tab-content {
 	flex: 1;
 	position: relative;
@@ -98,4 +104,9 @@ panel {
 
 .tabbedPanel.horizontal > .title > .tabList {
 	flex-flow: row;
+}
+
+.tabbedPanel > .title > .monaco-scrollable-element {
+	flex: 0 1 auto;
+	width: inherit;
 }