Fix - prevent setting 'none' as filter to main svg

filter used for inverse colors, but if 'none' -
nothing need to be set back

Author: linev

modules/draw.mjs

@@ -696,7 +696,7 @@ async function makeImage(args) {
          if (!mainsvg.attr('width') && !mainsvg.attr('height'))
             mainsvg.attr('width', args.width).attr('height', args.height);
 
-         if (style_filter)
+         if (style_filter && (style_filter !== 'none'))
             mainsvg.style('filter', style_filter);
 
          function clear_element() {

modules/gui/display.mjs

@@ -1281,7 +1281,7 @@ class BatchDisplay extends MDIDisplay {
       if (!mainsvg.attr('width') && !mainsvg.attr('height'))
          mainsvg.attr('width', this.width).attr('height', this.height);
 
-      if (style_filter)
+      if (style_filter && (style_filter !== 'none'))
          mainsvg.style('filter', style_filter);
 
       function clear_element() {