Wallboard-fastening device for securing wallboards in an inside-corner configuration

A wallboard-fastening device for securing first and second wallboards in an inside-corner configuration, comprising:

• a first framing panel having a first lengthwise edge;
• a second framing panel having opposite second and third lengthwise edges, the second lengthwise edge directly connecting to the first lengthwise edge;
• a first flat-spring flange having a fourth lengthwise edge directly connected to the third lengthwise edge such that the first flat-spring flange, the first framing panel, and the second framing panel form a channel sized to accept the first wallboard;
• and
• a second flat-spring flange having a fifth lengthwise edge directly connected to the third lengthwise edge;
• wherein:
• first flat-spring flange, when the first wallboard is absent from the channel, forms an angle with the second framing panel that is less than ninety degrees;
• the first flat-spring flange flexes, when the first wallboard is inserted into the channel, to push against the first wallboard;
• and
• the second flat-spring flange flexes, when a rear face of the second framing panel is pushed against the second wallboard, to push against the second wallboard.