ZeoGraph to-do list

In FilterTreeDlg:
- Change help link to direct to pages for specific filters (note: this requires filter to provide link to help page)
In CzFilter
- Add space for display flags and other temp settings used in ZeoGraphWnd (still required?)
For ZeoGraphWnd:
- Add 'Help→About' dialog box and menu item.
- Implement pin pass-through rendering, to show when maps are and aren't modified.
- Implement pin type negotiation (e.g. variants and hvars)
- Implement graph zooming.
- Add option to restore default filter name after using rename.
- Measure filter width to account for long filter names.
- Add tooltips for toolbar buttons.
- Add 'move filter' menu option.
- Allow multiple selection (for move/delete/disconnect options?)
- Add hotkeys:
  - 'o' for filter options.
  - 'r' for rename.
  - 'del' for delete.
  - 'd' for disconnect.
Provide some demo filters:
- Map
  - GetMosaicFormat
  - SetHorizScale
- File
  - ImportMosaic
  - ExportArea (wrapper for atExportArea)
- Heightfield
  - Clip
  - ErodeThermal
  - ErodeChannel
  - VolcanoOverlay
  - TerraceOverlay
  - MountainPass
  - TerracePass
  - PlateauPass
  - VolcanoPass
  - FileOverlayPass
  - ThermalPass
  - ChannelPass
  - FFT
Add options windows for filters:
- Map
  - CreateMap
  - CreateMosaic
- File
  - LoadMapFile
  - SaveMapFile
  - ExportMosaic
  - ImportMosaic
- Heightfield
  - Generate
    - Perlin
    - PerlinEx
    - Fractal

Won't do

Handle single left click on filter's 'options…' button — was wierd without proper button rendering of the options button.