Select Right-to-Left in the Options menu to quickly toggle text clips between left-to-right and right-to-left editing. What this command really does is switch the multi-line editor controls on the AceText Editor between the “default text layout for clip contents” and the “layout for opposite text direction” that you selected on the Appearance tab in the Preferences. The single-line editor control for the clip’s label is similarly switched between the “default text layout for clip labels” and its corresponding “layout for opposite text direction”. Because you’re switching between text layouts, the switch may change more settings than just the text direction. Other controls on the AceText Editor, including the URL field, do not switch text directions.
If you have at least one right-to-left keyboard layout installed in Windows then this command has a button on the main toolbar. You can then also switch text direction with the Ctrl and Shift keys on the keyboard. To switch to left-to-right, hold down either Ctrl key while pressing and releasing the left hand Shift key. To switch to right-to-left, hold down either Ctrl key while pressing the right hand Shift key. These key combinations too switch the editor controls between the “default text layout for clip contents/labels” and the “layout for opposite text direction”.
If you want right-to-left text to always be displayed legibly then both the default and opposite text layouts should be “complex script” text layouts, one right-to-left and the other left-to-right. Both support bidirectional text editing. The only difference is whether the text is left-aligned or right-aligned. The other left-to-right text layouts, however, do not support bidirectional text editing at all.