Attach the tag value for the following graphics objects drawn on the screen.
Tag value. Valid value range is from 1 to 255
Tag command can specify the value of the tag buffer of the FT800 that applies to the graphics objects when they are drawn
on the screen. This Tag value will be assigned to all the following objects, unless the TagMask command is used to disable it.
Once the following graphics objects are drawn, they are attached with the tag value successfully.
When the graphics objects attached with the tag value are touched, the register REG_TOUCH_TAG will be updated
with the tag value of the graphics object being touched.
If there is no Tag commands in one display list, all the graphics objects rendered by the display list will report tag value as 255
in REG_TOUCH_TAG when they were touched.