Open Windows Explorer through any means (Start -> Run -> explorer.exe or even just WINDOWS_KEY + E if you don't have any other file manager as the default)
Tools menu
Folder Options
File Types tab
Scroll down the list until you find the file type you're looking for - in your case, BMX. Select it with the left mouse button.
Click the button labelled Advanced
You should see a list of Actions:. Select open with the left mouse button.
Click the button labelled Edit
Under Application used to perform action:, change the program used (including full path) to be what you need it to be. Be sure to wrap it in quote marks (ie "). It should be followed by "%1" (including quotes), which indicates the filename of the BMX file you'll be double-clicking to open. For example, to get IDEal to open my .bb files, mine has "C:\Program Files\IDEal\IDEal.exe" "%1"
Click the button labelled OK, then OK again, then Close.
Live la vida loca.
(...which is what Ross said as I was typing this beast out. Bastage!)
Tools menu
Folder Options
File Types tab
Scroll down the list until you find the file type you're looking for - in your case, BMX. Select it with the left mouse button.
Click the button labelled Advanced
You should see a list of Actions:. Select open with the left mouse button.
Click the button labelled Edit
Under Application used to perform action:, change the program used (including full path) to be what you need it to be. Be sure to wrap it in quote marks (ie "). It should be followed by "%1" (including quotes), which indicates the filename of the BMX file you'll be double-clicking to open. For example, to get IDEal to open my .bb files, mine has "C:\Program Files\IDEal\IDEal.exe" "%1"
Click the button labelled OK, then OK again, then Close.
Live la vida loca.
(...which is what Ross said as I was typing this beast out. Bastage!)