Update 3 4 control perspective

3-4-control-perspective.md

@@ -83,6 +83,10 @@ You can right-click the *Legend* or the *Limit Range* to speed up the setting op
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 ![](img/3-4-right-click.png)
 
+> To Trang  
+> How about "### Controlling camera", and just giving it four sentences for each of "Zoom :", "Rotate : ", "Pan : ", "Zoom fit : "?  Actually "Zoom fit" cancel all the changes in zoom/rotate/pan and returns to the default camera position.
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