Comment # 1 on bug 887515 from Tony Morehen

This bug is still in effect in Tumbleweed.  I did a zypper up and it broke my
gambas installation.  Trying to run gambas by typing gambas3 in a terminal
window generates the same error message:  gbx3: unable to find startup file.

The problem:  In the openSuse installation, gambas3 is a symlink to gbx3.  When
installing from source, gambas3 is a symlink to gambas3.gambas.  Again in
openSuse, executing gambas3.gambas opens the gambas development environment.

There may also be menu issues. I have 2 gambas desktop files in my
/usr/share/applications folder.  The exec line in gambas3.desktop links to
gambas3.gambas and works fine.  The other, gambas.desktop, links to gambas3 and
is broken.  I don't know which is openSuse's.  Even ignoring the bug,
gambas3.desktop is the better file. 

Solution: correct the gambas3 symlink to gambas3.gambas.