Ensure consistent container height for branch menu and file list

Author: kgryte

src/style/BranchMenu.ts

@@ -97,6 +97,7 @@ export const newBranchButtonClass = style({
 export const listWrapperClass = style({
   display: 'block',
   width: '100%',
+  minHeight: '150px',
   maxHeight: '400px',
 
   overflow: 'hidden',

src/style/FileListStyle.ts

@@ -2,7 +2,12 @@ import { style } from 'typestyle';
 
 export const fileListWrapperClass = style({
   height: 'auto',
-  paddingBottom: '40px'
+  minHeight: '150px',
+  maxHeight: '400px',
+  paddingBottom: '40px',
+
+  overflow: 'hidden',
+  overflowY: 'scroll'
 });
 
 export const moveFileUpButtonStyle = style({