It's unclear why table manufacturers keep forgetting to secure glass to their table tops, but unfortunately they do. That sliding shard can be hazardous to curious toddlers and small children, or it could just be hazardous to your patience. If your table's loose pane is becoming a pain, a few options can help it, and you, stay grounded.
Clear Bonding Gel and Adhesives
Clear bonding gels can be a very strong adhesives. If you're looking to keep the glass top stuck to the table frame more permanently, this may be the best option. The makers of Museum Gel claim their product can hold glass in place even through an earthquake. A 4-oz. bottle of the clear bonding gel costs about $12 as of January 2010. UV Glass Glue also provides a strong permanent bond. However, UV Glass Glue runs from $17 to $200 a bottle, and needs an ultraviolet light source such as sunlight to cure correctly. A less toxic and permanent solution is to use adhesive putty like that made by Tac. This putty is removable and reusable, and quite cheap at less than $3 a package. One problem with putty is that it rarely comes in neutral or translucent colors--neon blues and greens are more common.
If you are looking for an option that can hold the glass in place for a long time yet is easily removed, consider just using small glass clamps and brackets. These are most often used to hold mirrors to walls or small panes of glass to the frames of storm doors. While they may not provide a smooth, seamless finish to the table, they are secure and inexpensive. Glass clamps and brackets can be found in any home improvement store.
Yes, that other great result of NASA's early experimentation has more uses than helping delay teaching your toddler to tie his shoes. Velcro mounting tape may be the most viable option for holding a glass table top to the frame. It's relatively cheap at less than $10 per roll and it's easily removable. It's also very helpful when cleaning. The glass top can be peeled or ripped up from the frame to clean underneath, then quickly restuck. Most Velcro mounting tape comes in only white or black, which presents no problem if your table frame happens to be one of these colors.