A funny thing happens if you’re using an empty Ajax Update Panel on your page/control definition in order to programmatically add controls from your code behind.
Any controls that are defined after the Update Panel will actually appear before it when the page renders.
I was losing my mind over this, not knowing if it was a css/styling error or whether I was just going crazy. However, none of that is true.
The Update Panel will (apparently) be populated after the controls that have been defined onto the actual page. In order to solve that, I had to add an asp Panel inside the Ajax Update Panel and programmatically add my controls inside the new asp Panel. Not into the Ajax Update Panel directly.
That way, when the page starts rendering, there is already a control inside the Ajax Update Panel and it will be inserted in the correct location. Afterwards, when the code starts adding controls in the asp panel (which is inside the Update Panel), everything will appear as expected.
