Keep track of theme filename within THEME_FILE.

diff --git a/dlls/uxtheme/system.c b/dlls/uxtheme/system.c
index 6bd3b78..531c1f8 100644
--- a/dlls/uxtheme/system.c
+++ b/dlls/uxtheme/system.c
@@ -152,7 +152,7 @@
         return hr;
     if(tf) {
         bThemeActive = TRUE;
-        GetModuleFileNameW(tf->hTheme, szCurrentTheme, sizeof(szCurrentTheme)/sizeof(szCurrentTheme[0]));
+        lstrcpynW(szCurrentTheme, tf->szThemeFile, sizeof(szCurrentTheme)/sizeof(szCurrentTheme[0]));
         lstrcpynW(szCurrentColor, tf->pszSelectedColor, sizeof(szCurrentColor)/sizeof(szCurrentColor[0]));
         lstrcpynW(szCurrentSize, tf->pszSelectedSize, sizeof(szCurrentSize)/sizeof(szCurrentSize[0]));
     }