Specifying a default working directory (Path) for Acrobat via acroread.desktop file

Acrobat starts always with ~ as the working directory. Because I keep all my pdf files in a seperate directory, I have to do quite some navigation before I can save them. This is especially bad as the Acrobat save as window displays all files including hidden files. Thus I would like Acrobat to use always ~/Documents/pdf as working directory. The .desktop file specification defines for Type=Application the entry Path= which is supposed to define the working directory. However, when I add the entry Path=~/Documents/pdf to the file /usr/share/application/acroread.desktop, it doesn't work. Apparently one has to give the complete path, because when i add Path=/home/jeltsch/Documents/pdf it works ok. However you should be aware that there might be more than one acroread.desktop files on your system, consequently you might have to modify more than one .desktop file. E.g. if you have a shortcut icon in your task bar/panel, the corresponding .desktop file will be probably somewhere under your home directory (~/.kde/share/apps/kicker). I posted a similar problem before to the xdg-list when I tried to specify the directory from which a shell script is executed and I got some feedback.