My recent experimentation with the cloud service took me to a revelation that says: "Well you should've known better!" At least I should be more careful setting up my system. Especially when being aware of the nature of things, but still let myself be sloppy.
It cost me some precious time and puzzled, achy head, but at the end the situation is already crystal clear to me.
I was trying to run NetBeans with portable JDK - both tools in the DropBox folder. It constantly refused to run saying it couldn't find a proper JDK.
At some point I decided to go with absolute paths in the netbeans.conf file. I did it very simply by defining in all my environments the variable $DROPBOX_BASE (with the actual corresponding value for every system of course). No more misty relative paths.
Still I didn't have success running the IDE. Hmm!
These days I'm experimenting with the new JBoss AS 7. Well taking the same approach there, the result that followed is obvious - the JBoss complained that it can not find a proper JDK unless I show it its position on the system with the --jdkhome command line option. Getting the same result after using the option in question, puzzled me the most. But it didn't take long until I realized that something wrong should be happening with some executable bits. Again some time and googling passed until I remembered that on the current (Linux) system I placed the Dropbox folder on NTFS partition, which was never even designed for the idea of executable bits being set as permissions.
So, my conclusion: when using DropBox on Linux, never set its folder on partitions designed for Windows OSes. You might still sync properly, but successfully executing binaries from it is very unlikely.