Alrighty, So first off I made a first slide of a comic I am making, I saved it as a .png file, then realized eh might as well just save as .pdn file, and then I saved it on the png file and closed paint.net, tried opening file, got this ->
System.ArgumentException: Parameter is not valid. at System.Drawing.Image.FromStream(Stream stream, Boolean useEmbeddedColorManagement, Boolean validateImageData) at PaintDotNet.Data.PngFileType.OnLoad(Stream input) in d:\src\pdn\paintdotnet\src\PaintDotNet\Data\PngFileType.cs:line 118 at PaintDotNet.FileType.Load(Stream input) in d:\src\pdn\paintdotnet\src\Data\FileType.cs:line 477 at PaintDotNet.Functional.Func.Eval[T1,TRet](Func`2 f, T1 arg1) in d:\src\pdn\paintdotnet\src\Base\Functional\Func.cs:line 158
So I read something about needing to manually change files, .png -> .pdn, BUT I HAVE NO IDEA HOW TO DO THAT, PLEASE HELP!