Add warning about pop-up ads

res/include/style/viewer.css

@@ -125,6 +125,13 @@
 	transform-origin: 0 0;
 }
 
+/* Pop-up warning (row 5) */
+.file_viewer > .popup_warn {
+	background-color: var(--layer_1_color);
+	border-top: 1px solid var(--layer_1_color_border);
+	text-align: center;
+}
+
 /* Toolbars */
 .file_viewer > .file_viewer_window > .file_viewer_toolbar {
 	position: absolute;

res/template/file_viewer.html

@@ -152,6 +152,13 @@
 					</div>
 				{{ end }}
 			</div>
+
+			{{ if and (and .Other.FileAdsEnabled .Other.UserAdsEnabled) (ne .Other.AdPopupType 0) }}
+				<div class="popup_warn">
+					You are viewing a large file ( > 250 MB ). Pop-up ads have been
+					enabled to cover bandwidth cost.
+				</div>
+			{{ end }}
 		</div>
 
 		<template id="tpl_details_popup">