In another thread the absence of a breakpoint capability has been noted. BBC BASIC does already support breakpoints in the form of the TRACE STEP statement, but these must be 'manually' inserted into the program where you want it to pause, and removed when no longer needed, so are obviously not as convenient as having the capability built into the IDE.
In fact this has been something on the SDLIDE 'wish list' for some time, but it has never acquired a high enough priority to be implemented. Both the LB Booster IDE and bbcide (the alternative BB4W IDE) do already support breakpoints so it isn't particularly challenging. I have created this poll to get a better idea of the degree of support for such an addition.