The file chooser in some apps gives an option 'customised files' or 'all files' - how to set default?

The file chooser in some apps gives an option selector button down in the bottom right marked 'customised files' or 'all files'.

The specific problem that this creates is as follows. My digital camera saves files with the JPG extension. When I want to upload those images e.g. with Google Chrome, they don't appear in the chooser window until I select 'all files'. So by default, the chooser only recognises files with .jpg as being valid, not .JPG.

I want the default to be 'all files' as this problem happens in other cases e.g. .pdf v .PDF. However, I would also accept being able to redefine the file type identifier or handler to recognise both upper and lower case extensions.

Any ideas?