The Overdue Invoice That Looked Just Like the Rest

The vendor contract tracker held thirty rows, each one a due date and a payment amount. Dana read down it every morning, hunting for a date that had slipped past and an amount that had crept over the ceiling. On Thursday she read it twice and still missed row 14: a due date six days gone, an invoice forty thousand dollars over the limit, both looking like every other row.

Adding the Conditional Formatting Button

A sheet that depends on someone rereading every row will eventually let one through. Dana's eyes are not the problem. The rule in her head, overdue means red, needs to run on every row each time the data changes, without her typing it in again. A fix has to attach the condition to the cell itself. Then the color appears the moment the data matches, not the moment someone remembers to check.

Synap Editor does exactly that from inside the table. A Conditional Formatting button sits next to the other table tools. It appears either in the main toolbar or in the small toolbar that shows up when you click into a cell. The button stays dim until you select a cell inside a table, and lights up the moment you do. It does not reach plain paragraph text, since the feature only activates inside a selected table cell.

Which Cells Should the Rule Cover?

Opening the button brings up the conditional formatting dialog, and the first thing it asks for is a range. Type it directly, like B2:B31 for the due date column, or click the range button next to the field to drag-select the cells on the table itself. While you drag, the table's row and column handles show numbers, so you can see exactly which cells you are about to cover.

A single rule is not limited to one block of cells. Add a comma after a finished range and the selection stays in place while you mark a second one. That way, one rule can watch two separate areas of the same table at once. For the contract tracker, the due date rule only needs the one column: B2:B31, the thirty rows of dates.

Flagging Overdue Dates with a Date Rule

With the range set to the due date column, the rule itself comes next. A Date rule offers calendar windows to compare against: Today, Yesterday, and Tomorrow. It also covers This week, Last week, Next week, and the month and year versions of the same idea. For the contract tracker, Dana's rule is Last week: any due date that fell inside the previous calendar week gets flagged. It is a calendar window, not a running count: a due date that passed three weeks ago falls outside Last week and stays unmarked. A tracker that must catch every late row needs a wider window, such as Last month, alongside it, and even that stops at the previous calendar month.

The rule only fires on a cell that is actually displaying as a date. If the due date column is formatted as plain text or a number, the Last week rule has nothing to compare and stays silent. Setting the column's display format to date first is what lets the rule read row 14's due date. Only then does it recognize that the date belongs to last week, instead of just seeing a number.

How to Flag Out-of-Range Amounts in Synap Editor

The payment amount column needs a different kind of rule, since it compares numbers instead of calendar windows. A Number rule covers comparisons like greater than, less than, equal, and the two range checks: Between and Not between. For the contract tracker, the agreed range per invoice has a minimum and a maximum. Any amount outside that range is the one that should stand out.

Dana sets the amount column's rule to Not between, with the two numbers that bound the normal range. Row 14's invoice, forty thousand dollars over the agreed maximum, fails the check the moment the rule runs. The cell then takes on the style attached to that rule. A Between rule works the same way in reverse, flagging values that fall inside a range instead of outside it.

Keep the Limit in a Cell, Not Inside the Rule

Typing the maximum straight into the Number rule works until the contract is renegotiated and the ceiling changes. At that point every rule that has the old number baked in has to be reopened and edited by hand.

Synap Editor also accepts a cell coordinate as the reference value, written as =E1. Instead of a fixed number typed into the rule, the rule reads its reference from cell E1 of the table. Dana keeps the agreed maximum in E1, next to the contract terms, so the ceiling is visible in the table and changing it does not mean reopening the rule. When a rule covers a whole column, confirm on a test row that every row compares against E1 itself rather than a shifted cell.

Which Rule Wins When Two Overlap?

Both rules now live in the Conditional Formatting List for the table, the due date rule above the amount rule. To see what the list does when two rules can fire on the same cell, Dana runs a quick test. She widens the amount rule's range for one row to also cover its due date cell.

On a cell that only one rule reaches, that rule's style just applies. On a cell that both rules reach, the list decides. The rule higher in the list wins on any property the two rules share, like background color. A property only one rule sets, like a bold font, applies regardless. Dragging a rule's handle up or down the list moves its priority.

[[shot: The shared test cell recolored by the amount rule after its entry is dragged above the date rule in the Conditional Formatting List]]

Moving the amount rule above the date rule on that test row changes which of the two colors appears on the shared cell. Neither rule's own settings need to change.

Confirm the Highlight, Then Add Your Own Rule

Back on the real tracker, row 14 now carries two colors without anyone clicking anything. The due date cell, six days past due and inside last week, shows the color attached to the Last week rule. The amount cell, forty thousand over the ceiling in E1, shows the color attached to the Not between rule. The other twenty-nine rows stay unmarked, because none of them break either rule.

[[shot: The vendor contract tracker with row 14's due date cell and amount cell both recolored while the surrounding rows stay plain]]

To build this in your own table, register the button first.

// synapeditor.config.js
{
  'editor.toolbar': [
    // ...
    'conditionalFormatting',
    // ...
  ]
}

The button appears in the toolbar and activates once a table cell is selected. Add it to the balloon instead to keep it next to the cell you're editing.

// synapeditor.config.js
{
  'editor.balloon': {
    'tableCell': [
      // ...
      'conditionalFormatting'
    ]
  }
}

The manual's Conditional Formatting section covers building the rules themselves, plus editing, reordering, and deleting them in full.

Common questions

Does a Date rule fire on a cell that isn't displaying as a date? No. A Date rule applies only when the cell's display format is date; a cell shown as plain text or a number is not compared against the calendar window.

Does Last week run Monday to Sunday or Sunday to Saturday? Sunday to Saturday. This week, Last week, and Next week are all defined as a Sunday-through-Saturday window.

Does the format style override a color I already set on the cell manually? Yes. The format style takes priority over any style already applied to the cell by hand.

Which Synap Editor release added conditional formatting? Conditional formatting is available from release 3.3.0 and above.