I am adding PNG support to a D6 program that already displays JPG, BMP and WMF in a TImage, and it works fine. When I use TOpenPictureDialog the program fails with EInvalidOp unknown picture extension (.PNG), even though I added this to the list of extensions Filter property via the Object Inspector. So, I modified my code to use TOpenDialog instead and it works fine - I have no problem selecting and opening the desired .png file into a TImage.
Can anyone advise why TOpenPictureDIalog fails ? Obviously, I have already discovered my solution - just to change my code to use TOpenDialog instead (especially as this offers a thumbnail view if I wish), so now I can't see the purpose of TOpenPictureDialog.
This is a bit of a newbie question, so your advice very much appreciated to help me understand why it failed.