this is trying to avoid crash by thread safety. related to #19266.

link to: http://172.17.66.192/biz/bug-view-19522.html

fix header bar and navigation bar didn't update state while entry search directory with terminal commandline.

	    [1] 修改一处内存的问题。
            [2] fixbug：11946 无法通过向侧边栏中的u盘drop file。

        [KEYWORDS ] drop file
        [TO SOLVE ] 11946
        [TEST SUGGESTION] 无法通过向侧边栏中的u盘drop file
        [SUBMIT BY] renpeijia
        [REVIEW BY] 兰悦
        [TEST   BY]

[LINK] 19193

this patch is trying to fix http://172.17.66.192/biz/bug-view-17745.html.

    repair recycle bin can be copied and cut using shortcut or the edit menu
 [LINK]
    18396

note that we need consider a better way to resolve this problem.

This reverts commit e8804ea7.

This reverts commit f7446863.

    Link：http://172.17.66.192/biz/story-view-2763-1-project-455.html
    本次修改内容：[1]添加copyright header
                  [2]添加研发需求链接

    [KEYWORDS ] thumbnail
    [TO SOLVE ] thumbnail
    [TEST SUGGESTION] 不同格式的office文件和视频文件
    [SUBMIT BY] renpeijia
    [REVIEW BY] 兰悦
    [TEST   BY]

    [2] 视频文件缩略图显示的时，开发显示视频中图片的的功能

    [KEYWORDS ] thumbnail
    [TO SOLVE ] thumbnail
    [TEST SUGGESTION] 不同格式的office文件和视频文件
    [SUBMIT BY] renpeijia
    [REVIEW BY]
    [TEST   BY]

Link: Bug #18035.

[LINK] 18207

this patch will help list view has same fluency as icon view.

Link:Bug #12092, #15273.

Link:http://172.17.66.192/biz/bug-view-17505.html

Link:http://172.17.66.192/biz/bug-view-17918.html

FIXME: we have to handle the logic error sence we use cache and timer to positive enumeration.

this will help to avoid frequent flashment when displaying a "huge" directory view，
such as a search directory view.