shift+space should insert a space

src/gui/Window.cc

@@ -384,7 +384,7 @@ uint32_t Window::get_keyval(SDL_Keycode keysym)
     if ((m_keymod & (KMOD_SHIFT | KMOD_CAPS)) != 0u)
     {
         uint32_t shifted = get_shifted(keyval);
-        if (shifted != keyval)
+        if (shifted != 0u)
         {
             keyval = shifted;
         }
@@ -475,7 +475,8 @@ uint32_t Window::get_shifted(uint32_t keysym)
     case SDLK_BACKSLASH:    return '|';
     case SDLK_RIGHTBRACKET: return '}';
     case SDLK_BACKQUOTE:    return '~';
+    case SDLK_SPACE:        return ' ';
     }
 
-    return keysym;
+    return 0u;
 }