As I'm working thru my WebPart development, I occasionally received an error: Object Reference not set to an instance of an object.
Turns out that the order of events in the WebPart class are slightly different when the tool part is being displayed:
| “Regular“ mode |
“ToolPane“ mode |
| New |
New |
| On Init |
On Init |
| On Load |
CreateChildControls |
| CreateChildControls |
On Load |
|
GetToolParts |
| On PreRender |
On PreRender |
| RenderWebPart |
RenderWebPart |