FS/2 will automatically warn you with a dialog when the amount of memory (RAM plus swap space) available to the system falls below a preset level, even if FS/2 is minimized or is reduced to the Swap Window and another application is the active window.
Available
Memory Warning
The default preset warning level of available memory is 6 MB; this value, as well as the frequency of the swap data update, may be raised or lowered in the FS/2 Settings Notebook. Setting the value to 0 disables the memory alert feature. The available memory data is checked at intervals of 4 x update frequency.