Main screen: Come back to the same tab after exiting a game

Leaving a game creates a new MainScreen, which picked the default tab
(Recent unless changed) whenever there were recent files. Remember the
tab for the rest of the session, so the default tab only applies to the
first main screen after startup.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

UI/MainScreen.cpp

@@ -189,12 +189,23 @@ static bool IsTempPath(const Path &str) {
 	return false;
 }
 
+// Leaving a game creates a new MainScreen, which should come back on the tab the game was
+// launched from. The default tab setting is only for the first one after startup.
+static int g_lastMainScreenTab = -1;
+// Tab indices shift when the Recent tab isn't shown, so the saved tab only applies if this matches.
+static bool g_lastMainScreenHadRecent = false;
+
 MainScreen::MainScreen() {
 	g_BackgroundAudio.SetGame(Path());
 	packGeneration_ = GamePacker::Generation();
 }
 
 MainScreen::~MainScreen() {
+	// RemoteISOBrowseScreen derives from us, but with tabs of its own.
+	if (tabHolder_ && createdMainTabs_) {
+		g_lastMainScreenTab = tabHolder_->GetCurrentTab();
+		g_lastMainScreenHadRecent = recentTabShown_;
+	}
 	g_BackgroundAudio.SetGame(Path());
 }
 
@@ -445,6 +456,8 @@ void MainScreen::CreateViews() {
 	if (showRecent) {
 		CreateRecentTab();
 	}
+	recentTabShown_ = showRecent;
+	createdMainTabs_ = true;
 
 	Button *focusButton = nullptr;
 	if (hasStorageAccess) {
@@ -457,7 +470,9 @@ void MainScreen::CreateViews() {
 			remoteBrowser->SetHomePath(remotePath);
 		}
 
-		if (g_recentFiles.HasAny()) {
+		if (g_lastMainScreenTab >= 0 && g_lastMainScreenHadRecent == showRecent) {
+			tabHolder_->SetCurrentTab(g_lastMainScreenTab, true);
+		} else if (g_recentFiles.HasAny()) {
 			tabHolder_->SetCurrentTab(std::clamp(g_Config.iDefaultTab, 0, g_Config.bRemoteTab ? 3 : 2), true);
 		} else if (g_Config.iMaxRecent > 0) {
 			tabHolder_->SetCurrentTab(1, true);