When needed, clear buffer before rendering menu

SourceX/DiabloUI/credits.cpp

@@ -208,6 +208,7 @@ void CreditsRenderer::Render()
 		return;
 	prev_offset_y_ = offset_y;
 
+	SDL_FillRect(GetOutputSurface(), NULL, 0x000000);
 	DrawArt(PANEL_LEFT + 0, 0, &ArtBackground);
 	if (font == NULL)
 		return;

SourceX/DiabloUI/diabloui.cpp

@@ -606,6 +606,12 @@ void DrawSelector(const SDL_Rect &rect)
 	DrawArt(rect.x + rect.w - art->w(), y, art, frame);
 }
 
+void UiClearScreen()
+{
+	if (SCREEN_WIDTH > 640) // Background size
+		SDL_FillRect(GetOutputSurface(), NULL, 0x000000);
+}
+
 void UiPollAndRender()
 {
 	SDL_Event event;

SourceX/DiabloUI/diabloui.h

@@ -56,6 +56,7 @@ void UiFocusNavigationEsc();
 void UiFocusNavigationYesNo();
 void UiInitList(int min, int max, void (*fnFocus)(int value), void (*fnSelect)(int value), void (*fnEsc)(), UiItem *items, int size, bool wraps = false, bool (*fnYesNo)() = NULL);
 void UiInitScrollBar(UiScrollBar *ui_sb, std::size_t viewport_size, const std::size_t *current_offset);
+void UiClearScreen();
 void UiPollAndRender();
 void UiRenderItems(UiItem *items, std::size_t size);
 

SourceX/DiabloUI/mainmenu.cpp

@@ -70,6 +70,7 @@ BOOL UiMainMenuDialog(char *name, int *pdwResult, void (*fnSound)(char *file), i
 		mainmenu_restart_repintro(); // for automatic starts
 
 		while (MainMenuResult == 0) {
+			UiClearScreen();
 			UiPollAndRender();
 			if (!gbSpawned && SDL_GetTicks() >= dwAttractTicks) {
 				MainMenuResult = MAINMENU_ATTRACT_MODE;

SourceX/DiabloUI/progress.cpp

@@ -66,6 +66,7 @@ void progress_Free()
 
 void progress_Render(BYTE progress)
 {
+	SDL_FillRect(GetOutputSurface(), NULL, 0x000000);
 	DrawArt(0, 0, &ArtBackground);
 
 	int x = GetCenterOffset(280);

SourceX/DiabloUI/selconn.cpp

@@ -116,6 +116,7 @@ int UiSelectProvider(
 	selconn_ReturnValue = true;
 	selconn_EndMenu = false;
 	while (!selconn_EndMenu) {
+		UiClearScreen();
 		UiPollAndRender();
 	}
 	selconn_Free();

SourceX/DiabloUI/selgame.cpp

@@ -285,6 +285,7 @@ int UiSelectGame(int a1, _SNETPROGRAMDATA *client_info, _SNETPLAYERDATA *user_in
 
 	selgame_endMenu = false;
 	while (!selgame_endMenu) {
+		UiClearScreen();
 		UiPollAndRender();
 	}
 	selgame_Free();

SourceX/DiabloUI/selhero.cpp

@@ -367,6 +367,7 @@ BOOL UiSelHeroDialog(
 
 		selhero_endMenu = false;
 		while (!selhero_endMenu && !selhero_navigateYesNo) {
+			UiClearScreen();
 			UiRenderItems(SELHERO_DIALOG, size(SELHERO_DIALOG));
 			UiPollAndRender();
 		}

SourceX/DiabloUI/selok.cpp

@@ -75,6 +75,7 @@ void UiSelOkDialog(const char *title, const char *body, bool background)
 
 	selok_endMenu = false;
 	while (!selok_endMenu) {
+		UiClearScreen();
 		UiRenderItems(items, itemCnt);
 		UiPollAndRender();
 	}

SourceX/DiabloUI/selyesno.cpp

@@ -55,6 +55,7 @@ bool UiSelHeroYesNoDialog(const char *title, const char *body)
 	selyesno_value = true;
 	selyesno_endMenu = false;
 	while (!selyesno_endMenu) {
+		UiClearScreen();
 		UiRenderItems(SELYESNO_DIALOG, size(SELYESNO_DIALOG));
 		UiPollAndRender();
 	}