Updating matched brace highlighting following cursor movement via a mouse click

I suppose this is a specific extension of an unanswered question from a while back. It turns out a left mouse click causes a call to ViewFilter.ExecCommand with the command ID ECMD_LEFTMOUSE. I tried adding a case VsCommands2K.ECMD_LEFTCLICK in ViewFilter.HandlePostExec where the rest of the brace matching command IDs (several keystrokes) are handled, but it was never called. It turns out that the following call in ExecCommand returns 0x80020100, which I found listed in NativeMethods as OLECMDERR_E_NOTSUPPORTED:

this.InnerExec(ref guidCmdGroup, nCmdId, nCmdexecopt, pvaIn, pvaOut)

This causes ExecCommand to return without calling ViewFilter.HandlePostExec. Does anyone have an idea why this happens (what happens inside InnerExec?), or how might this situation be handled?