message: selection ui tooltip tweaks
diff: @@ -173,10 +173,10 @@ export class StructureSelectionActionsControls extends PluginUIComponent<{}, Str
  return <>
  <div className='msp-flex-row' style={{ background: 'none' }}>
  <PureSelectControl title={`Picking Level for selecting and highlighting`} param={StructureSelectionParams.granularity} name='granularity' value={granularity} onChange={this.setGranuality} isDisabled={this.isDisabled} />
  - <ToggleButton icon={Union} title={ActionHeader.get('add')} toggle={this.toggleAdd} isSelected={this.state.action === 'add'} disabled={this.isDisabled} />
  - <ToggleButton icon={Subtract} title={ActionHeader.get('remove')} toggle={this.toggleRemove} isSelected={this.state.action === 'remove'} disabled={this.isDisabled} />
  - <ToggleButton icon={Intersect} title={ActionHeader.get('intersect')} toggle={this.toggleIntersect} isSelected={this.state.action === 'intersect'} disabled={this.isDisabled} />
  - <ToggleButton icon={SetSvg} title={ActionHeader.get('set')} toggle={this.toggleSet} isSelected={this.state.action === 'set'} disabled={this.isDisabled} />
  + <ToggleButton icon={Union} title={`${ActionHeader.get('add')}. Hold shift key to keep menu open.`} toggle={this.toggleAdd} isSelected={this.state.action === 'add'} disabled={this.isDisabled} />
  + <ToggleButton icon={Subtract} title={`${ActionHeader.get('remove')}. Hold shift key to keep menu open.`} toggle={this.toggleRemove} isSelected={this.state.action === 'remove'} disabled={this.isDisabled} />
  + <ToggleButton icon={Intersect} title={`${ActionHeader.get('intersect')}. Hold shift key to keep menu open.`} toggle={this.toggleIntersect} isSelected={this.state.action === 'intersect'} disabled={this.isDisabled} />
  + <ToggleButton icon={SetSvg} title={`${ActionHeader.get('set')}. Hold shift key to keep menu open.`} toggle={this.toggleSet} isSelected={this.state.action === 'set'} disabled={this.isDisabled} />
  <ToggleButton icon={Brush} title='Color Selection' toggle={this.toggleColor} isSelected={this.state.action === 'color'} disabled={this.isDisabled} style={{ marginLeft: '10px' }} />
  <ToggleButton icon={CubeSvg} title='Create Representation of Selection' toggle={this.toggleAddRepr} isSelected={this.state.action === 'add-repr'} disabled={this.isDisabled} />
  