code: public void openGalleryDialog(CmsResource resource) {
  
          try {
              CmsObject cms = A_CmsUI.getCmsObject();
              JSONObject conf = new JSONObject();
              conf.put(I_CmsGalleryProviderConstants.CONFIG_GALLERY_MODE, GalleryMode.view.name());
              conf.put(I_CmsGalleryProviderConstants.CONFIG_GALLERY_PATH, cms.getSitePath(resource));
              conf.put(I_CmsGalleryProviderConstants.CONFIG_GALLERY_STORAGE_PREFIX, "");
              conf.put(I_CmsGalleryProviderConstants.CONFIG_TAB_CONFIG, CmsGalleryTabConfiguration.TC_SELECT_ALL);
              getRpcProxy(I_CmsGwtDialogClientRpc.class).openGalleryDialog(conf.toString());
          } catch (JSONException e) {
              CmsErrorDialog.showErrorDialog(e);
          }
      }
docs: Opens the gallery dialog for the given gallery folder.<p>
  
  @param resource the gallery folder resource