Hi, I've been searching this function a long time, so as I find it now, I share this tip.

Actually when you plug the tablet to your computer you have only one option : is Mass storage.

I prefer MTP (on Windows 7) because, the sd card is still available for yours applications on your tablet.
On my phone, I have a option in status bar when I connect it to my computer. Here nothing.

The option is somewhere else.

After opening the right settings bar, Click on Settings to open the setting page

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Then select Storage.

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Then click on the option buttons (on the upper right : the icon with 3 points)
A menu appears : USB computer connection, click it.

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And we got it !

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You can now select your prefered method for transferring files.

Then, the link in the notification bar will direct you to that page.

That's it !