I'm using sap gui in macbook os x. Whenever I execute the web dynpro programs, the browser will be opened and is keep on loading and it never ends. How can I fix this issue?
Though your Safari version seems actual, I assume your MacOS version is not supported by SAP, as PAM lists only versions from 10.11.
SAP issues PAM (Product Availability Matrix) sheets where you can match your Browser, Platform and Product versions and check for inconsistencies. Netweaver 7.4 PAM can be found here.
Probably, your MacOS version is too old for SAP and you should try to update. However, personally I feel that problem lies elsewhere and you should ask for help of experienced BASIS. Maybe your WDA uses certain feature that is not supported by Safari or WDA in general.
Additionally you can check: