sokol_app.h win32.h: fix GlobalUnlock parameter in clipboard code (fixes #810)

sokol_app.h

@@ -7518,26 +7518,32 @@ _SOKOL_PRIVATE bool _sapp_win32_set_clipboard_string(const char* str) {
     SOKOL_ASSERT(_sapp.win32.hwnd);
     SOKOL_ASSERT(_sapp.clipboard.enabled && (_sapp.clipboard.buf_size > 0));
 
+    if (!OpenClipboard(_sapp.win32.hwnd)) {
+        return false;
+    }
+
+    HANDLE object = 0;
     wchar_t* wchar_buf = 0;
+
     const SIZE_T wchar_buf_size = (SIZE_T)_sapp.clipboard.buf_size * sizeof(wchar_t);
-    HANDLE object = GlobalAlloc(GMEM_MOVEABLE, wchar_buf_size);
-    if (!object) {
+    object = GlobalAlloc(GMEM_MOVEABLE, wchar_buf_size);
+    if (NULL == object) {
         goto error;
     }
     wchar_buf = (wchar_t*) GlobalLock(object);
-    if (!wchar_buf) {
+    if (NULL == wchar_buf) {
         goto error;
     }
     if (!_sapp_win32_utf8_to_wide(str, wchar_buf, (int)wchar_buf_size)) {
         goto error;
     }
-    GlobalUnlock(wchar_buf);
+    GlobalUnlock(object);
     wchar_buf = 0;
-    if (!OpenClipboard(_sapp.win32.hwnd)) {
+    EmptyClipboard();
+    // NOTE: when successful, SetClipboardData() takes ownership of memory object!
+    if (NULL == SetClipboardData(CF_UNICODETEXT, object)) {
         goto error;
     }
-    EmptyClipboard();
-    SetClipboardData(CF_UNICODETEXT, object);
     CloseClipboard();
     return true;
 
@@ -7548,6 +7554,7 @@ error:
     if (object) {
         GlobalFree(object);
     }
+    CloseClipboard();
     return false;
 }