It had to happen sooner or later. But now questions about how to do this are appearing. And the answer is “it depends”.
ALWAYS use a copy or have a backup copy of your entire project JUST in case something goes wrong.
IF you have a license that permits you to save as text (Xojo Project) save your project as a text project. You then need to open the single file called projectname.xojo_project
At the very beginning of this file you will see entries like the following :
Type=Desktop RBProjectVersion=2019.02 MinIDEVersion=20190200 OrigIDEVersion=20190200
Change the number after MinIDEVersion to 20070100 and save. You can now open the project in whatever version you want.
In an XML project you would see
<?xml version="1.0" encoding="UTF-8"?> <RBProject version="2019r2" FormatVersion="2" MinIDEVersion="20190200"> <block type="Project" ID="0">
Again change the number following MinIDEVersion to 20070100. Make sure you keep the quotes around the value. And save.
Binary is a lot tougher because it is a proprietary format. And to edit that you WILL need a licensed version of Arbed. Once you have that you can open a binary project and select the top entry which represents the project and change the OriginalVersion to 20070100 and the ProjectSavedInVers to 2007.01 and save.
And now you can open your project in old versions again.