STEP SEQUENCER
The Step Sequencer is the main part of FL Studio' interface. It contains a button for each channel in your song, from which you can call its Channels Settings, Piano Roll etc. It also contains a pattern grid, where you can create drum loops and simple melodies.
Each line in the Step Sequencer represents a single channel with its pattern grid. Each button in the grid represents a 16-th note. The default pattern length is 16 dots, but you may change this setting from the Project General Settings window. Additionally, you can set a custom length for each individual pattern with the Pattern Length control (1).
Left-clicking a grid button turns it on; right-clicking turns it off. Note that if you have turned off Use Both Mouse Keys option in the General Settings page, left-clicking turns both on and off the buttons.
You can also set the button's note (pitch) using the Keyboard Editor view. Each note has some additional properties (panning, volume etc.) that you can set using the Graph Editor view.
Right-clicking the Channel Button (11) brings up a menu that provides some commands for managing channels (see Channel Menu). Additionally, this menu provides access to the Piano Roll window which is designed for entering of complex melodic parts (unlike the sequencing grid, which is optimized for quick entering of drum loops and basic bass lines).
The main Edit menu also contains commands for working with Step Sequencer.
Having too much channels can make the work in the Step Sequencer slow and tedious. To optimize your workflow and project structure, you can combine several channels in a group and set the Step Sequencer to display only specific group of channels (for example percussion group or lead synth group). To control which channels should be visible you can use the Channel Display Filter control (7). Left-click to open the channel filter menu. Selecting "All" shows all channels at once, no matter if they are part of any group or unassigned. Selecting "Unsorted" displayed only the unassigned channels. Also, if you have made any channel groups, you can select them for display from this menu. To add empty group, right-click and select Add Filter Group. With the group displayed, right-click the Channel Display Filter control to see commands for renaming and deleting a group (deleting a group won't delete the channels in it, but make them unassigned). To add all selected channels to a group, use the Group Selected command from the Channels menu.
When adding new channels, they are inserted in the currently selected group.