Since the latest version of Gallery supports HTML5 multi-file uploads and it is enabled by default and the HTML5/Flash options are exclusive then the phrase xengallery_upload_image_explain that describes Flash uploads should....
- ... have a corrresponding HTML5 phrase (xengallery_upload_image_explain_html5?) that is displayed instead when the HTML5 option is selected in the ACP.
- ... or replace the description of the existing phrase with a more generic wording ("Use the button above to upload an image. If your browser supports it you will be able to upload multiple images at the same time."?).