[R] Display of NAs in character columns of a data frame under fix() or edit().

[Rolf Turner]

Example:

	xxx <- data.frame(x=1:26,y=letters)
	xxx$x[c(2,4,6,8)] <- NA
	xxx$y[c(1,3,5,7)] <- NA

	yyy <- edit(yyy)

The missing values in xxx$y appear as blanks in the spreadsheet window that
appears, whereas the missing values in the numeric column "x" appear as "NA"
(as I would expect).

Is this a bug or a feature?

	cheers,

		Rolf Turner

P.S.

> sessionInfo()
R version 2.12.0 (2010-10-15)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

locale:
[1] en_NZ.UTF-8/en_NZ.UTF-8/C/C/en_NZ.UTF-8/en_NZ.UTF-8

attached base packages:
[1] datasets  utils     stats     graphics  grDevices methods   base     

other attached packages:
[1] misc_0.0-13     gtools_2.6.2    spatstat_1.20-5 deldir_0.0-12  
[5] mgcv_1.6-2      fortunes_1.4-0  MASS_7.3-8     

loaded via a namespace (and not attached):
[1] grid_2.12.0        lattice_0.19-13    Matrix_0.999375-44 nlme_3.1-97       
[5] tools_2.12.0