1.2.0RC4 is built against sdk10.5. The 1.3.0 is built using sdk10.7 in Xcode that will be upgraded shortly to sdk10.8 (pending a few deprecation warnings to be resolved). User Preferences determine scrollbar characteristics for the OS. The setting consists of the following options:
- Automatically based on input device
- When scrolling
- Always
So the first option will depends on whether you have a trackpad or mouse. For example, with a mouse attached:

The second option provides the result on the second image you have included that is much like iOS:

The scrollbars are not specific to WebKit. In fact, the images above were created from code compiled against the native WebKit that is very much up to date. We will be releasing TideSDK and TideSDK Lite shortly. If you do not need the php, python or ruby language support, you will want TideSDK Lite. TideSDK Lite is also our product for gaining AppStore approval.