Finally got a handle on how to create custom buttons and they go a reasonable way toward a solution. Only limitation seems to be you are limited to five custom time intervals.
With the darker grey buttons (3m, 30m, 2h) I think the dark grey is indicating a possible error situation which I’ll explain in a moment.
In case anyone is wondering how to do something similar, here is what I did.
Please note, this is not a tutorial – simply a basic account of what I have learnt from experimenting today.
First step is to define your five preferred custom time intervals in Tools > Preferences > Intraday.
Then open the customize window via Tools > Customize
Then pull down the list of timeframes via View > Intraday. Now you can drag n drop each timeframe to the Tool Bar.
Once all the buttons are on the Tool Bar, with the Customize window still open, you can right click on each button to bring down the button editing options.
I just wanted simple buttons so I changed the text to something simple eg 1h for hourly, and enabled Text only.
Now the possible error condition I mentioned earlier is that I tried to create more than five custom timeframes by going back to Tools > Preferences and editing some timeframes. (Restart required to enable them in menus.)
However, this attempt at a workaround was unsuccessful as each button is linked to a Custom Periodicity. If you change the Custom Periodicity in Preferences, the label on the button will refer to the new periodicity and not match the label description on the button.
So in this example, buttons 3m, 30m and 2h all refer to Custom Periodicity 1 which is now set to 30m. So buttons 3m and 2h will give you the wrong chart display. (Mouse over tells you which Custom Periodicity is linked to that button.)
Anyway, it’s a start. Others may have more experience with this and be able to shine more light on the subject.