A method, comprising: at a computing system comprising one or more processors, memory, a first housing that includes a primary display, and a second housing at least partially containing (i) a physical keyboard and (ii) a touch-sensitive secondary display distinct from the primary display: receiving a request to open a file associated with a content-editing application; in response to receiving the request: displaying, on the primary display, first content of a first type and second content of a second type, that is distinct from the first type, from the file within the content-editing application; and displaying, on the touch-sensitive secondary display, a user interface comprising multiple user interface elements each associated with a respective content-display parameter for modifying presentation of content within the content-editing application; detecting a first input that selects the first content of the first type while it is displayed within the content-editing application on the primary display; in response to detecting the first input, displaying a first control, on the touch-sensitive secondary display, associated with a first content-display parameter for modifying presentation of the content of the first type; detecting a second input that selects the second content of the second type while it is displayed within the content-editing application on the primary display; and in response to detecting the second input, concurrently displaying a plurality of controls, on the touch-sensitive secondary display, associated with a second content-display parameter, different from the first content-display parameter, for modifying presentation of the content of the second type, wherein the plurality of concurrently displayed controls includes a second control and a third control; while displaying the plurality of controls, detecting selection of one of the plurality of controls; in response to detecting selection of one of the plurality of controls: in accordance with a determination that the second control is selected, performing an operation in the second content of the second type; and in accordance with a determination that the third control is selected, replacing display of the first control in the touch-sensitive secondary display with one or more controls for performing a different operation on the second content of the second type without performing the operation in the second content of the second type. receiving a request to open a file associated with a content-editing application; in response to receiving the request: displaying, on the primary display, first content of a first type and second content of a second type, that is distinct from the first type, from the file within the content-editing application; and displaying, on the touch-sensitive secondary display, a user interface comprising multiple user interface elements each associated with a respective content-display parameter for modifying presentation of content within the content-editing application; displaying, on the primary display, first content of a first type and second content of a second type, that is distinct from the first type, from the file within the content-editing application; and displaying, on the touch-sensitive secondary display, a user interface comprising multiple user interface elements each associated with a respective content-display parameter for modifying presentation of content within the content-editing application; detecting a first input that selects the first content of the first type while it is displayed within the content-editing application on the primary display; in response to detecting the first input, displaying a first control, on the touch-sensitive secondary display, associated with a first content-display parameter for modifying presentation of the content of the first type; detecting a second input that selects the second content of the second type while it is displayed within the content-editing application on the primary display; and in response to detecting the second input, concurrently displaying a plurality of controls, on the touch-sensitive secondary display, associated with a second content-display parameter, different from the first content-display parameter, for modifying presentation of the content of the second type, wherein the plurality of concurrently displayed controls includes a second control and a third control; while displaying the plurality of controls, detecting selection of one of the plurality of controls; in response to detecting selection of one of the plurality of controls: in accordance with a determination that the second control is selected, performing an operation in the second content of the second type; and in accordance with a determination that the third control is selected, replacing display of the first control in the touch-sensitive secondary display with one or more controls for performing a different operation on the second content of the second type without performing the operation in the second content of the second type. in accordance with a determination that the second control is selected, performing an operation in the second content of the second type; and in accordance with a determination that the third control is selected, replacing display of the first control in the touch-sensitive secondary display with one or more controls for performing a different operation on the second content of the second type without performing the operation in the second content of the second type.