Insert > Formatting Mark has a host of goodies for extra control over your text flow, such as a non-breaking space or hyphen.
First, set up OpenOffice so you can get all the options. Choose Tools > Options > Language Settings > Languages and select the indicated Enabled for Complex Text Layout option. Click OK.
Now choose Insert > Formatting Mark and choose the one you want.
You can see the keyboard shortcuts on the menu, and here are a couple as described in the Help.
* Nonbreaking space: To prevent two words from being separated at the end of a line, press the Ctrl key when you type a space between the words.