I think I know why now. I've found an answer in other forum, and though I didn't find the code of FormView, I've found a DetailsView implementation and I think in this case it might be similar.
Basically what I've understood of it, is that the ModeChanged/ing events are raised when command buttons are clicked (Cancel, Edit, Insert, New and Update), i.e. when one doesn't have direct control over these events, and when we use the ChangeMode method, we know that the mode has changed (or will be changed) and it would make no sense of raising an event..
DetailsView ChangeMode:
public void ChangeMode(DetailsViewMode newMode) {
Mode = newMode;
}
DetailsView command handlers:
private void HandleCancel() {
bool isBoundToDataSourceControl = IsBoundUsingDataSourceID;
DetailsViewModeEventArgs e = new DetailsViewModeEventArgs(DefaultMode, true);
OnModeChanging(e);
if (e.Cancel) {
return;
}
if (isBoundToDataSourceControl) {
Mode = e.NewMode;
OnModeChanged(EventArgs.Empty);
}
RequiresDataBinding = true;
}
private void HandleEdit() {
if (PageIndex < 0) {
return;
}
DetailsViewModeEventArgs e = new DetailsViewModeEventArgs(DetailsViewMode.Edit, false);
OnModeChanging(e);
if (e.Cancel) {
return;
}
if (IsBoundUsingDataSourceID) {
Mode = e.NewMode;
OnModeChanged(EventArgs.Empty);
}
RequiresDataBinding = true;
}
private bool HandleInsertCallback(int affectedRows, Exception ex) {
DetailsViewInsertedEventArgs dea = new DetailsViewInsertedEventArgs(affectedRows, ex);
dea.SetValues(_insertValues);
OnItemInserted(dea);
_insertValues = null;
if (ex != null && !dea.ExceptionHandled) {
if (PageIsValidAfterModelException()) {
return false;
}
dea.KeepInInsertMode = true;
}
if (!dea.KeepInInsertMode) {
DetailsViewModeEventArgs eMode = new DetailsViewModeEventArgs(DefaultMode, false);
OnModeChanging(eMode);
if (!eMode.Cancel) {
Mode = eMode.NewMode;
OnModeChanged(EventArgs.Empty);
RequiresDataBinding = true;
}
}
return true;
}
private void HandleNew() {
DetailsViewModeEventArgs e = new DetailsViewModeEventArgs(DetailsViewMode.Insert, false);
OnModeChanging(e);
if (e.Cancel) {
return;
}
if (IsBoundUsingDataSourceID) {
Mode = e.NewMode;
OnModeChanged(EventArgs.Empty);
}
RequiresDataBinding = true;
}
private bool HandleUpdateCallback(int affectedRows, Exception ex) {
DetailsViewUpdatedEventArgs dea = new DetailsViewUpdatedEventArgs(affectedRows, ex);
dea.SetOldValues(_updateOldValues);
dea.SetNewValues(_updateNewValues);
dea.SetKeys(_updateKeys);
OnItemUpdated(dea);
_updateKeys = null;
_updateOldValues = null;
_updateNewValues = null;
if (ex != null && !dea.ExceptionHandled) {
if (PageIsValidAfterModelException()) {
return false;
}
dea.KeepInEditMode = true;
}
if (!dea.KeepInEditMode) {
DetailsViewModeEventArgs eMode = new DetailsViewModeEventArgs(DefaultMode, false);
OnModeChanging(eMode);
if (!eMode.Cancel) {
Mode = eMode.NewMode;
OnModeChanged(EventArgs.Empty);
RequiresDataBinding = true;
}
}
return true;
}