add on_focus method to slider to do things on focus events

Author: sspickle

.gitignore

@@ -4,6 +4,7 @@ bower_components
 *.pyc
 .DS_Store
 /venv
+/.venv
 __pycache__/
 *~
 /.vscode/

lib/glow/primitives.js

@@ -3381,7 +3381,7 @@
 	    var cvs = canvas.get_selected()
 	    var attrs = {pos:cvs.caption_anchor, aria_label:"", aria_labelledby:"", aria_describedby:"", length:400, width:10, vertical:false, disabled:false,
 	    			 min:0, max:1, align:'none', top:0, right:0, bottom:0, left:0, range_color:vec(0,0,0),
-					 handle_color:vec(0, 0x6c/0xff, 0xfa/0xff)}
+					 handle_color:vec(0, 0x6c/0xff, 0xfa/0xff), on_focus:undefined}
 	    if (args.bind !== undefined) {
 	    	attrs.bind = args.bind
 	    	delete args.bind
@@ -3484,7 +3484,11 @@
 		if (attrs.aria_describedby) {
 			$( `#${attrs._id} .ui-slider-handle`).attr('aria-describedby', attrs.aria_describedby._id)
 		}
-	    
+
+	    if (attrs.on_focus) {
+            $(`#${attrs._id} .ui-slider-handle`).on('focus',attrs.on_focus)
+	    }
+
 	    var cslider = {
 	    	get disabled() {return attrs.disabled},
 	        set disabled(value) {