Since iOS 13 released, I have paid lots of attention to the new modal view inside it. The new modal view appears with new animation that creates a 3D sense. The defination of this new modal view in Apple HIG( Human Interaction Guidelines ) is as follow"Modality is a design technique that presents content in a temporary mode that’s separate from the user's previous current context and requires an explicit action to exit."————Apple HIG  Breaking current user flow which is what modality does always should be the last choice when designing a flow. Because breaking could make users lose direction for the next step of their tasks. However, we have to break the flow in some necessary contexts. I think Apple did a good job to make users less confused by designing usable interaction of modality.
 However, when the modality used by third-party developers, some accidents happens. Douban APP, the first app I found using the new sheet of modality. I found new modality applied in Douban just after iOS 13 released when few apps use new modality.
 I appreciate the pioneer spirit of Douban designers. But there is a mistake about modality usage. In the details page of a work, when pressing the "more" button located in the top right corner, a sheet modal view covering half screen will come out.  This interaction breaks Fitts's law by creating a long path to move."Fitts's law predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target."————Wikipedia  As shown in the picture below, we have to adjust the holding gesture to reach the button above. But after tapping the button, the modal view comes out from the bottom. We have to adjust gesture again for further actions.
 Designers of Taobao did a better job than Douban did. They present a shorter path after the previous action.
 Besides, with the size of cellphones becomes bigger, interaction requiring changing gestures would make users annoyed. Instead in the new version of Samsung OneUI, designers divide the screen into two areas for viewing and interacting respectively. Also, they put action buttons in the area that could be comfortably reached.
 In all, seemingly unimportant mistakes like this might be devastating because users might drop their phones on the ground when changing gestures like me. I wonder if there is a possibility to develop a tool for checking this kind of mistake automatically to help designer save their time on these issues.