As usual, that DG lesson raises more questions than it answers. Plus, it didn't work for me.
(1) For some reason, to create a column TEMPLATE, instead you click column BEHAVIOR. Is a template the same thing as a behavior? If not, then what's the difference? And why are we clicking BEHAVIOR to create a TEMPLATE? No clue.
(2) When I click to create a new Column Behavior, my screen looks completely different from the screenshot. My template group is several lines high, it's pretty wide, and the label is all the way on the right. Does this matter? Should I try to resize my template group to be only 1 line high if I want it to be only one line high in the DG? No clue.
(3) I drag a checkbox into the template group area, then try to close the template group editing window. I'm surprised that I'm prompted to Save the stack. Of course this isn't mentioned in the lesson. So I save the stack so I can close the template group editing window. But after saving, the editing window is still open. Ugh. Close the window again, this time it closes without complaint. But my checkbox doesn't appear in the DG. Is it because there's no data in the DG? I add some, still no checkbox. I decide to go back to the template group editing window to make sure the checkbox is still there, but this time when I click the Column Behavior button, instead of showing me the template group editing window, I see a script editor window. No clue how to get back to the template group editing window.
(4) Okay, I'll delete the DG and start over. Of course that doesn't work either: A bug in the IDE means that no DG appears when I drag it out of the toolbox. Restart LiveCode and start over again from scratch.
(5) Create a new stack, create a DG, add two columns, populate, and Save so I can restart from here after the next inevitable roadblock. Follow the instructions again and see that I missed that I'm supposed to do Edit Group twice for some reason that's not explained. Do that, but then it's the end of the instructions. No clue how to add a button, except for the unhelpful, "At this point you can customize what controls appear in the column template." With no better ideas, I drag a checkbox on top of the column label. Try to close the editing template, and again for some reason I'm prompted to save. Click Save, and then THE IDE CRASHES, stuck on the "Saving..." box forever.
This is why people hate the DG and the documentation. I hope someday LC makes a DG-type control that's native rather than grafted on, with LC-style syntax rather than its own special syntax, and intuitive operation rather than column behavior row template gobbledegook.