In newer versions of Visual Studio (VS2012 and VS2013 at the time of writing), When you drag/drop one of Atalasoft's WinForms viewers onto your forms designer, it can sometimes fail to show up.

There are several possible causes for this...

NOTE: the following applies to Visual Studio 2019 and older

Visual Studio 2022 is a 64 bit process so the instructions below need to be reversed - instead of x86 you want x64

ALSO NOTE: The designer DOES NOT WORK for .NET 5 / .NET 6 / .NET 7 projects at this time

for more information on that please see:

FAQ: Support for ASP.NET Core / .NET Core / .NET 5 / .NET 6

Correcting the issue:

The first thing to do is to check that you're not targeting x64. We have x64 dlls and absolutely support building x64 apps with DotImage, but the VS forms designer is running in 32 bit and can't understand our x64 dlls. (this actually can happen in ALL versions of VS, not just 2012 and 2013)

To address this situation set your platform target to x86 or AnyCPU while working in the designer and use our x86 DLLs.

The next case (if you're ensured you've got the "bitness" sorted) is to ensure you add references to ALL of the following DLLs:

Atalasoft.dotImage.dll
Atalasoft.dotImage.Lib.dll
Atalasoft.dotImage.WinControls.dll
Atalasoft.Shared.dll

You may need to restart Visual Studio after adding those references if the drag/drop still doesn't work.

As a next step,

• If you right click on the project in Solution Explorer and go to Properties, it pulls up the Project Properties page...
• Navigate to the Reference Paths section.
• Add the explicit path to the top bar either pasting or browse.
  if you are using VS2019 or older (32 bit) use C:\Program Files (x86)\Atalasoft\DotImage 11.4\bin\4.5.2\x86
  if you are using VS2022 or newer (64 bit) use C:\Program Files (x86)\Atalasoft\DotImage 11.4\bin\4.5.2\x64
• Once you've picked the path you must hit the Add option.
• This will force the dlls to come from the right place.
• you may also need to go back to your references in Solution explorer and select properties on each and set "use specific version" to False.

Finally, if you've done all that and when you drag/drop the designer still refuses to work and/or if you see an error saying it can't add the reference to Atalasoft.dotImage.WinControls.dll because it's already there, Go ahead and remove the reference to Atalasoft.dotImage.WinControls.dll, restart VS and try again.

If you're still having issues after following these guidelines, create s support case (please make sure you reference this KB article, indicating you've already tried following it.

For more information, please see:

INFO: Bitness Roundup Whitepaper: x86, x64, AnyCPU

Original Article:
Q10406 - FIX: Drag-Drop of Some Atalasoft Viewers Not Adding Control to Designer