Here is a way to get the blank funtionality you want. Create a script with the following lines.
Attributes Output, Layer = currentLayer
XSelect Layers = currentlayer
Attributes Layer = currentLayer, Blank=TRUE
You can tie the script to any icon or shortcut you like. Before running the script just select the layer you want to blank in the dropdown menu (Extra Tool bar). Then when you run the script it will blank the current layer in that window.