Preform 1.5x lost ability to 'add' additional models?

I have been using Preform since pre 1.x and I love the ability to add additional models by double click or drag .stl file into the current print job. This saves having to print several jobs and I can simply leave the single large print over long weekend.

After upgraded to 1.5.2, I could not find this feature anywhere / reproduce the old behavior by any mean (drag, double click, menu, etc…)

Is there a reason for this removal or am I missing something in the software?

I have version 1.5.2 on Windows 7 and it all works good, I just tested for you. I usually use the File >> Open to do this type of thing. If the model is .STL it adds it with no questions asked. If it is a .FORM file it will ask if you want to merge or clear.

I did notice double-clicking will open a new preform window without question, but I consider that normal behavior since what is happening is you are telling Windows to execute the program file on the hard drive, which is going to be a new instance.

Thanks @JoshK. I opened the file using the menu and it worked. Not sure what I missed before.

There is an issue with drag and drop not working on windows 8 that sadly is outside of our control (it’s an issue with the UI library we use). We will periodically try to see if the underlying issue was fixed. In the meantime, you can add additional models to the see through the menu.

I am actually on Mac. If I recall correctly, in the old version, i could drag and drop the model, but no longer possible in 1.5.x

It does indeed not show the (+) icon anymore when dragging form files (it is shown for obj and stl files), however it still works. I added the missing visual feedback to our bug tracker, thanks!

@Manuel_Odendahl it doesn’t work at all on my Mac. I tried dragging .stl and .form to existing workspace but it is showing the blocking cursor and when I released, nothing happened.

If I do this on the dock icon, it will simply replace the current workspace instead of adding to it.

Hi Kent,

can you contact me at so that I can ask you more questions, and not overburden the forum?

Regards, Manuel