a bit of hero window

help needed - make something to prevent changing surface stored in CHeroWindow::background. I do not overwrite it, but it changes dramatically with every call of CHeroWindow method!

And besides - is there anything to make my window displayed easily, without calling show() every frame when it should be displayed? any machanism?

CHeroWindow.cpp

@@ -0,0 +1,32 @@
+#include "stdafx.h"
+#include "CHeroWindow.h"
+#include "SDL.h"
+#include "SDL_Extensions.h"
+
+extern SDL_Surface * ekran;
+
+CHeroWindow::CHeroWindow()
+{
+	background = SDL_LoadBMP("Data\\HEROSCR4.bmp");
+	pos.x = 0;
+	pos.y = 0;
+	pos.h = background->h;
+	pos.w = background->w;
+}
+
+CHeroWindow::~CHeroWindow()
+{
+	SDL_FreeSurface(background);
+}
+
+void CHeroWindow::show(SDL_Surface *to)
+{
+	if(!to)
+		to=ekran;
+	blitAt(background,pos.x,pos.y,to);
+}
+
+void CHeroWindow::setHero(const CGHeroInstance *hero)
+{
+	curHero = hero;
+}