Disable media context menus in IV.

Telegram/Resources/iv_html/page.js

@@ -330,6 +330,7 @@ var IV = {
 							+ '" type="video/mp4" />'
 						+ '</video>';
 					var media = element.firstChild;
+					media.oncontextmenu = function () { return false; };
 					media.oncanplay = IV.checkVideos;
 					media.onloadeddata = IV.checkVideos;
 				}

Telegram/SourceFiles/iv/iv_prepare.cpp

@@ -516,6 +516,7 @@ QByteArray Parser::block(
 	const auto id = Number(photo.id);
 	result = tag("a", {
 		{ "href", href },
+		{ "oncontextmenu", data.vurl() ? QByteArray() : "return false;" },
 		{ "data-context", data.vurl() ? QByteArray() : "viewer-photo" + id },
 	}, result) + caption(data.vcaption());
 	return result;
@@ -576,6 +577,7 @@ QByteArray Parser::block(
 		const auto href = resource("video" + id);
 		result = tag("a", {
 			{ "href", href },
+			{ "oncontextmenu", "return false;" },
 			{ "data-context", "viewer-video" + id },
 		}, result);
 	}
@@ -745,6 +747,7 @@ QByteArray Parser::block(const MTPDpageBlockAudio &data) {
 	const auto src = documentFullUrl(audio);
 	return tag("figure", tag("audio", {
 		{ "src", src },
+		{ "oncontextmenu", "return false;" },
 		{ "controls", std::nullopt },
 	}) + caption(data.vcaption()));
 }