Is it possible using Xojo to enhance the base Windows Save As dialog or to have an additional dialog displayed whenever a Save As dialog is displayed in Windows. I would also like to do the same on a Mac. Thanks
Not without declares or a plug-in.
Ok so it is possible to replace the default Save As dialog in windows and mac across the OS?
Ive seen Mac dialogs with option buttons at the bottom.
It would not be trivial to hook every running process for code injection to make a custom save across the entire windows OS.
What are you trying to achieve, there may be a different route to what you are asking.
I have a need to be able to record document information eg title, description, client id, time spent etc every time a document is created with the ability for an exclude list (ideally) so that certain applications will just use the normal Save As dialog. I will have no idea what application software is installed on the clients PC/Mac so needs to be done at a very low level.
Ah, I didnt get that you wanted to change Windows and macOS itself. I suspect that you cant do that with Xojo.
Hmmm, just off the top of my head, create a system tray app that would incorporate a folder watcher that will monitor for new files and prompt the user for the information you mention above after the file has been written.
Or create a Shell Extension Handler Metadata Handler which I think is just registry mods and ini files (not really played around with it)
-EDIT-
A Shell Extension Handler is out of the question in Xojo as you need to create a DLL 
For a client I added an extension to the open dialog for Windows.
See OpenDialogMBS class.
So you set UseCustomPicture to a number to add this as extra space to the dialog.
Than we use CustomPicture property for the picture to show there.
Technically this could be enhanced to show more if needed.
Just create your own custom dialog and manage the save yourself. That’s what I do for a couple of “hardware” related apps where normal filesystem dialogs are not quite what I need.
That won’t fly on Mac though. Translocation, Quarantine, Gate Keeper and all that.
Which of us are you replying to?
Guys, please get that he wants to replace the save dialog SYSTEM WIDE and not just in his own apps.
Like what the app Default Folder (see Default Folder X) is doing on the Mac.
The app Default Folder shows it is possible (at least on Macs) but I have no clue as to how they do it.
But have a look at https://alternativeto.net/software/default-folder-x/ and especially for Windows at
Btw I suspect that with the increased emphasis on security most apps like these will stop working as it probably requires using non-private APIs etc
Thanks everyone, I have come to the conclusion that what I am trying to do is not possible so the other option is to create a file watcher program that monitors a folder for changes and then pops up a dialog. Not clean but may be the only way.
The initial post said that he would like to target Mac as well, so it was a mixture of your post about a custom dialog and the needs for OP.