Question

I would like to programmatically change “Ignore other applications that use DDE” using C# for Excel 2007 (12) any suggestions?

Answer 1

I have never done it, but this article seems promising:

http://blogs.vmware.com/thinapp/2008/10/excel-dde-worka.html

I basically searched for changing the settings via the registry. You can perform registry edits through C#, so that may be able to do it.

I will admit I am not 100% this is what you are looking for, but it seemed like the same setting.

UPDATE AFTER SITE WAS REMOVED, CONTENT FROM WAYBACK MACHINE POSTED BELOW:

For those who have needed a workaround to the DDE file type issue surrounding Excel, please download the .reg file below and follow these directions. Remember, you can always script this into your .exe if you rather have this run at first launch. Just be sure to use the ExecuteExternalProcess function to have it apply to your local system.

Use ThinReg as usual to register file types (Or MSI installer)
Download the linked ExcelDDEOpen.reg file, open the .reg file using notepad
Change the path to "Microsoft Office Excel 2007.exe", remember to use "\" instead of "" to separate directories
Save ExcelDDEOpen.reg
Add entries to registry by double-clicking the modified ExcelDDEOpen.reg file
The attached code for ExcelDDEOpen.reg file is set up to use per-user registry entries. If you want per-machine registry entries, change all occurrences of HKEY_CURRENT_USER to HKEY_LOCAL_MACHINE

Please create a file called ExcelDDEOpen.reg and paste this info into it.

———Copy Below———-

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\SOFTWARE\Classes\xls.ThinReg\shell\Open]

@="&Open"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xls.ThinReg\shell\Open\command]

@="\"C:\\Path\\to\\virtual\\package\\Microsoft Office Excel 2007.EXE\" /e"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xls.ThinReg\shell\Open\ddeexec]

@="[open(\"%1\")]"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xls.ThinReg\shell\Open\ddeexec\application]

@="Excel"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xls.ThinReg\shell\Open\ddeexec\topic]

@="system"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xlsx.ThinReg\shell\Open]

@="&Open"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xlsx.ThinReg\shell\Open\command]

@="\"C:\\Path\\to\\virtual\\package\\Microsoft Office Excel 2007.EXE\" /e"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xlsx.ThinReg\shell\Open\ddeexec]

@="[open(\"%1\")]"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xlsx.ThinReg\shell\Open\ddeexec\application]

@="Excel"

[HKEY_CURRENT_USER\SOFTWARE\Classes\xlsx.ThinReg\shell\Open\ddeexec\topic]

@="system"