在车机端测试show，删除按钮的时候按钮的边框未删除

[zhuangzhuangyong]

[Delete any non-applicable sections, but we may ask for more information.] 测试前提:车机端右侧已经使用show功能添加了按钮

Bug Report

[Summary] 在车机端show了SOFTBUTTON后，删除按钮的时候按钮的边框未删除

Reproduction Steps

1. [Step 1] 正常启动QTHMI程序，并点击Application
2. [Step 2] 在手机上启动SyncProxyTester App，选择Wifi并输入SDL的IP地址，并点击OK
3. [Step 3] 在车机端启动APP
4. [Step 4] 在手机端点击SEND MESSAGE按钮
5. [Step 5] 点击Show按钮
6. [Step 6] 点击Clear SOFT BUTTONS选择框,将选择框勾选上，然后更换图片,点击OK按钮

Expected Behavior

[Some expected behavior] 车机端右侧显示按钮完全消失

Observed Behavior

[Some observed behavior] 车机端右侧显示按钮边框未消失

OS & Version Information

• OS/Version: [The OS/Version you were running when the bug occurred] 魅族（MEIZU PRO 6s）/ Android6.0 /ubuntu 16.04 LTS 64位
• SDL Core Version: [The version of SDL Core you were using when the bug occurred]
• SDL Proxy Version：[The version of SDL Android/ SDL iOS you were using when the bug occurred]
• Testing Against: [What you tested with to observe this behavior. Proxy, App, HMI etc.]

Test Case, Sample Code, and / or Example App

[Paste a link to a PR, gist, or other code that exemplifies this behavior]