The three 2D views show cross sections of the image data along the X, Y, and Z axes. The upper-left view, with the red border around the image data, shows a slice perpendicular to the X axis. The lower-right view (green) shows a slice perpendicular to the Y axis, and the upper-right view (blue) shows a Z slice. When the mouse cursor hovers over a 2D view, its border turns yellow indicating the window has become active. The following interaction is possible in an active 2D view:

• zooming using the mouse wheel (when in paint/erase mode, the paintbrush size will change instead; see below).
• panning using the middle mouse button or right mouse button,
• scrolling through the image slices using the Page Up/Down keys.
• pressing the ESC key will exit the interaction mode, i.e. cancel the selection of a segmentation seed, poi, or landmark location.
• pressing the R key will reset the camera view.
• pressing the HOME/END key will move to the first/last image slice.
• pressing the Ctrl + z key will undo the last segmentation edit.
• pressing the Ctrl + Y key will redo the last undone segmentation edit.
• pressing the X key will flip the image along the X axis.
• pressing the Y key will flip the image along the Yh axis.
• pressing the Z key will flip the image along the Z axis.
• pressing the P key when a label is selected in the Segmentation widget toggles paint mode. The current mode is displayed on the right side of the status bar at the bottom of the main window. In this mode you can label additional voxels in the segmentation by pressing the left mouse button. It is also possible to drag the mouse while keeping the left button depressed. The radius of the paintbrush can be changed while in paint mode using the mouse wheel. It can also be changed in the dialog accessible by selecting Options → Settings in the menu bar.
• pressing the E key when a label is selected in the Segmentation widget toggles erase mode. The current mode is displayed on the right side of the status bar at the bottom of the main window. In this mode you can unlabel voxels in the segmentation by pressing the left mouse button. It is also possible to drag the mouse while keeping the left button depressed. The radius of the paintbrush can be changed while in erase mode using the mouse wheel. It can also be changed in the dialog accessible by selecting Options → Settings in the menu bar.
• pressing the M key when a label is selected in the Segmentation widget activates manual hole filling mode. The current mode is displayed on the right side of the status bar at the bottom of the main window. In this mode you can use the left mouse button to select holes in the segmentation that need to be filled.
• pressing the S key toggles the display of the segmentation labels.
• pressing the H key toggles the display of on-screen help text.