how to dispaly data in grid

Hi, all

In import function, some wxGrid is used to display preview data.
I consider it is better that all of wxGrid in the pgAdmin
should use same data style.

Now, there is a option called "Show NULL values as <NULL>".
But it only affect query tool. The issue is:
If checked, the string "<NULL>" and NULL can't be distincted.
If not, empty string and NULL can't be distincted.

In data grid, this option is ignored.
NULL is displayed as blank, empty string as ''.
If the data is two single quotation marks, it is displayed as \'\'.
Other amount, no change with original data.(''' as ''', '''' as '''', and so on)

So, we should define some rules to deal this.

Regards.

-----------------------------------------------
Quan Zongliang
quanzongliang@gmail.com
CIT Japan:  http://www.cit.co.jp
CIT China:  http://www.citbj.com.cn