@Hawkeye64 Cool, thanks! That certainly takes it to another level.

So, I want to filter the tree by both a Search input box and / or a value passed by a button click that represents a status property on the leaf nodes. (Actually, there are 5 such buttons, each representing a different status, but for simplicity’s sake we pretend there is just one status value.)

This is the stripped-down solution.

<!-- The search input box -->
<q-input
  v-model="searchBox"
  label="Filter"
></q-input>

<!-- The button to filter where node status = 1 -->
<q-button @click="onClickStatus(1)">
  Status 1
</q-button>

<!-- The tree -->
<q-tree
  ref="projectTree"
  :filter="filterTrigger"
  :filter-method="customFilterMethod"
 ....
></q-tree>

export default {
  data () {
    return {
      searchBox: '',
      filterTrigger: 'true',
      statusFilter: ''
      ....
    }
  },

  watch: {
    // Whenever the searchBox property changes, 
    // use it to trigger the tree filter's reactivity
    // by assigning its value to the 
    // filterTrigger property. 
    // Actually, the value we assign here is irrelevant.
    searchBox: function (newVal, oldVal) {
      this.filterTrigger = newVal
    }
  },

  methods: {
    onClickStatus (statusId) {
      // This method is more complicated than this in reality,
      // but basically we track which of the 5 status' were clicked
      this.statusFilter = statusId
    },

    customFilterMethod (node, filterTrigger) {
      // The filterTrigger param is ignored in here.

      // Instead, we use the contents of the search box input ...
      const searchBoxText = this.searchBox.toLowerCase()

      const matchedNodeLabel = (node.label && node.label.toLowerCase().indexOf(searchBoxText) > -1)

      // And any status button that was clicked ....
      let matchedStatus = true

      if (this.statusFilter !== '') {
        // if the node status is in the list of filters, match it
        // Very simplified example code:
        matchedStatus = (this.statusFilter.indexOf(node.status) > -1)
      }

      // In our context we always AND the filters
      return (matchedNodeLabel && matchedStatus)
    }
  }
}

Now, if there is something typed into the search box, or if a status button is clicked, either or both of those values will be used to filter the tree nodes. Yay!

@metalsadman
Wow! That’s awesome. Thank you.
I already had the sticky header but left it out of my example to keep it simple. I thought the issue of the sizing was with flex but clearly I was wasting time trying to make that happen! Much appreciated.
Go well,
Murray