Thank you, Erel. Yes "BtnDate" has Event Name "BtnDate", and "ACTxtLocn" has Event Name "ACTxtLocn". The Designer also still shows them as still having the correct Parent, "PnlLog". Nothing there has changed since they were working.
No, there is no visualization when either component is clicked.
But, good news. I have experimented by moving things around on the panel. I have a working EditText and Button at the top of the panel. If I swap them around with the dead views, suddenly the previously-dead ones start working and the previously-working ones die ! If one of the dead components is put at the top of the panel with the two working ones, then it too starts to work. So the cause of the views becoming unresponsive is obviously their position on the panel - which apart from my recent experimenting hasn't changed since when they were working.
I am concluding that the cause of the trouble is a ListView2: this is added by code and does not show in the designer so is easily forgotten. Its basic rectangle does indeed cover where the two affected views are placed. I can move the two views to below the space set aside for the ListView2 and they work again.
So, I have a working app, but it looks a bit strange with most of the screen empty most of the time - the ListView2 only visually appears when called up and then only if there is any relevant data to display. So the answer seems to be to keep the ListView2 height to a bare minimum when it is not being used, and resize it when needed, or a series of .SendToBack and .SendToFront commands, or even to only .Add it to the Panel when needed and remove it when not. As to why this wasn't necessary before but has become necessary now that will have to remain a mystery I think. I posted a query the other day involving this ListView2, maybe I tinkered with its settings when I had a problem with it - I really don't remember. Age is not being kind to my brain cells.
Thanks again.
Caravelle